Spherical Component Of Refraction Research Articles

A clinical case of a combined method for correcting postkeratoplastic astigmatism of a high degree in a patient with cataract

Background. Performing penetrating keratoplasty in 100 % of cases leads to the occurrence of induced postkeratoplasty astigmatism, which can be more than 12,0 D. If cataracts occur in this category of patients, performing cataract phacoemulsification with implantation of a toric intraocular lens (tIOL) does not completely solve the problem. The use of the method of implantation of intrastromal corneal segments at stage I before cataract phacoemulsification makes it possible to reduce the degree of postkeratoplasty astigmatism and create optimal conditions for additional correction of residual postkeratoplasty astigmatism due to the implantation of tIOL during cataract phacoemulsification.The aim. To analyze the clinical and functional indicators of correction of regular high-grade postkeratoplasty astigmatism in a patient with cataracts using a combined method, including first implantation of intrastromal corneal segments and subsequent cataract phacoemulsification with implantation of toric intraocular lens using the example of a clinical case.Material and methods. A 55-year-old patient with cataracts, who had a history of undergoing penetrating keratoplasty, contacted us. According to the keratotopogram data, a regular postkeratoplasty astigmatism of 18.68 D was diagnosed. The patient underwent a combined method. At stage I, intrastromal corneal segments were implanted into the corneal graft, then after 6 months stage II was performed – cataract phacoemulsification with implantation of tIOL.Results. Six months after intrastromal corneal segments implantation, the patient’s keratometric data stabilized, and corneal astigmatism decreased to 8.98 D. Then the patient underwent cataract phacoemulsification with tIOL implantation. After 1 month, the spherical component of refraction was 0.5 D, the cylindrical component of refraction was –0.5 D, visual acuity increased to 1.0.Conclusions. A combined method for correcting regular high-grade postkeratoplasty astigmatism in a patient with cataracts showed high refractive results, stability and safety in the long-term postoperative period.

An Integrated Stepwise Approach to the Treatment of Graft Disease in a Patient with an Implanted Iris Lens Diaphragm and Concomitant Postkeratoplastic Ametropia (Clinical Case)

The purpose: to analyze the clinical and functional results of the complex staged treatment of graft disease in patient with an implanted iris lens diaphragm and concomitant postkeratoplastic ametropia using descemet’s stripping endothelial keratoplasty using a femtosecond laser (FS-DSEK) and MyoRing implantation into a corneal graft using a femtosecond laser on the example of a clinical case. Methods. Patient M., 51 years old, was admitted with a diagnosis of the left eye: corneal transplant disease, condition after penetrating keratoplasty, iridoartifakia, avitria, optic nerve subatrophy, high myopia. To treat the graft disease, the patient underwent FS-DSEK using a FemtoVisum 1 MHz (Troitsk, Russia). Twelve months after FS-DSEK to correct irregular postkeratoplastic astigmatism and concomitant high-grade myopia detected after restoration of the transparency of the penetrating corneal graft, the MyoRing was implanted into the penetrating corneal graft using a femtosecond laser. Results. After performing FS-DSEK, the transparency of the penetrating corneal graft was completely restored, visometry, refractokeratometry, and keratopachymetric data were stabilized by 6 months after the operation. 12 months after FS-DSEK, uncorrected visual acuity (UCVA) increased from 1.6 to 1.2 LogMAR, best corrected visual acuity (BCVA) increased from 1.6 to 0.8 LogMAR. Loss of endothelial cell density of the posterior layered graft was 27.4 %. MyoRing implantation into a penetrating corneal graft made it possible to significantly increase the UCVA from 1.3 to 0.3 LogMAR and the BCVA from 0.8 to 0.2 LogMAR. The spherical component of refraction decreased from -6.25 to -0.75 D, the cylindrical component of refraction — from -9.25 to -1.25 D, the regularity, sphericity of the corneal graft and its biomechanical properties increased (corneal resistance factor increased from 8.2 to 9.4 mm Hg, corneal hysteresis — from 7.9 to 9.1 mm Hg). Conclusion. A complex staged technique of descemet’s stripping endothelial keratoplasty using a femtosecond laser followed by MyoRing implantation into the corneal graft using a femtosecond laser is an effective and safe method for treating graft disease in a patient with an implanted iris lens diaphragm and concomitant postkeratoplastic ametropia.

Наш опыт имплантации торических интраокулярных линз

Рurpose. To analyze the results of cataract phacoemulsification with implantation of toric intraocular lenses. Methods. We conducted a retrospective analysis of the results of cataract phacoemulsification with concomitant regular corneal astigmatism of 1.5 D or more. 32 patients (42 eyes) were implanted with toric intraocular lenses: 11 MX 60T lenses (BAUSCH+LOMB) and 31 Torica aAY lenses (HumanOptics). Results. Intraocular lens rotation less than 5 ° was recorded in 40 eyes (95.2 %). In 2 patients, the deviation of Torica aAY lenses was 10–15 °, which required their surgical reposition. All patients achieved an increase in uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA). UCVA after surgery increased by an average of 0.5 (from 0.13±0.03 to 0.63±0.08), and then remained stable. BCVA increased by 0.33 (from 0.37±0.06 to 0.7±0.06) in the early postoperative period, and by another 0.09 (0.79±0.04) in the late period. Mean value of the spherical component of refraction decreased in the early postoperative period by 4.1 D (from 5.05±0.45 to 0.94±0.22), in the late period a slight increase by 0.09 D was recorded. The value of the cylindrical component decreased after the operation by an average of 2.24 D (from 3.31±0.22 to 1.07±0.37), further a decrease by another 0.1 D was observed. Conclusion. The implantation of toric intraocular lenses is a relatively inexpensive, technically uncomplicated, effective and safe method of cataract surgery and associated corneal astigmatism correction. Key words: phacoemulsification; astigmatism; toric intraocular lens.

Phacoemulsification in patients after previous implantation of a complete intrastromal ring into a corneal transplant

BACKGROUND: The MyoRing implantation into a corneal transplant can significantly compensate for irregular post-keratoplastic astigmatism. However, the cataract that occurs in this category of patients and the lack of information in the literature on its phacoemulsification and the calculation of a toric intraocular lens (tIOL) power in them determines the relevance of our study.
 AIM: The aim of the study is to conduct a clinical and functional analysis of phacoemulsification in patients after previously performed implantation of a MyoRing into a corneal transplant.
 MATERIALS AND METHODS: We operated on 21 patients (21 eyes) who had previously undergone the MyoRing implantation into a corneal transplant. According to keratotopography, all patients were diagnosed with a regular form of corneal astigmatism. All patients underwent phacoemulsification with tIOL implantation. When calculating the tIOL power, its diopter value was corrected depending on the average value of the corneal transplant keratometry according to the keratotopogram data. The observation period duration was 6 months.
 RESULTS: One month after the procedure, there was an increase in uncorrected visual acuity by 0.2 0.9 LogMAR, best corrected visual acuity by 0.3 1.0 LogMAR, the spherical component of refraction up to 0.4 0.44 D, the cylindrical component of refraction up to 0.62 0.18 D, all of which did not change later on.
 CONCLUSIONS: Phacoemulsification with tIOL implantation, with its power calculated taking into account an additional correction for its diopter value, is an effective, predictable and safe method of treating patients after previously performed MyoRing implantation into a penetrating corneal transplant.

OPTICAL-REFLECTION METHOD OF ACCOMMODATIVE FACILITY TRAINING ON MERIDIONAL ACUITY IN TREATMENT OF ASTIGMATS WITH AMBLYOPIA

ackground: The efficacy of accommodative facility training as a method of treatment for meridional amblyopia (MA) in astigmatic children with amblyopia was studied. MA manifests itself as selective alterations in visual acuity (VA), with substantial differences in the ability to resolve contours of different orientations, and may cause impairments in mechanisms of integrated processing of visual stimulus, development of cognitive abilities in children and visual performance. Purpose: To assess the effect of optical-reflection method of accommodative facility training on vernier acuity in meridians (MVA) in the treatment of astigmatic children with amblyopia. Material and Methods: Twenty seven children aged 5 to 12 years, with both refractive amblyopia and with-the-rule hyperopic astigmatism were included in the study, and underwent an examination. The spherical component of refraction ranged from +0.5D to +5.5D, and the cylindical component, from 0.5D to 4.5D. Best-corrected visual acuity (Sivtsev Chart) was assessed. Accommodative facility training was performed monocularly by image defocusing with lenses of a variable power. A +0.5-D sphere was placed just in front of the best correction for the study eye in order to blur this line. The +0.5-D sphere was replaced by a -0.5-D sphere after the optotypes became clearly visible. Thereafter, the training cycle was repeated using a ±0.75-D sphere and, subsequently, a ±1.0-D sphere. Lens power was gradually increased until it could be compensated by accommodation. The treatment course consisted of one training session a day for 10 days. Special computer software was used to determine corrected MVA. Linear objects were presented on the computer screen, and the smallest lateral displacement of one line from another that can be detected by the examinee will characterize the level of MVA. Results: A new algorithm was proposed for assessing the efficacy of treatment of MA in astigmats, with refractive asymmetries and meridional asymmetries in vernier acuity considered as vector quantities. It was demonstrated that a group of amblyops with the same type of astigmatism was not homogeneous. It was found possible to split such a group of patients into three clusters that differ in the type of variation in meridional acuity in the orthogonal meridians compared to refractive asymmetries. One cluster had equal vernier acuities in the vertical and horizontal meridians, the second had vernier acuity in the horizontal meridian better than in the vertical meridian, and the third had vernier acuity in the horizontal meridian worse than in the vertical meridian. MVA was greater in magnitude in one of the orthogonal meridians than in another in the dominant eyes in 37% of study patients, and in the fellow eyes in 50% of study patients. MVA values in the orthogonal meridians were similar in 56.6% of study patients. There was a 15.1-percent increase, from 56.6% to 71.1% in the number of eyes with a similar vernier acuity in the orthogonal meridians after treatment. A positive effect was achieved through elimination of meridional asymmetry in vernier acuity in a portion of patients from clusters that differ in the direction of meridional asymmetry in vernier acuity. In addition, the number of eyes in the category of patients with a visual acuity of 0.75-0.8 (as assessed with complex optotypes) increased by 11.35%. Conclusion: The efficacy of treatment for MA should be assessed in homogeneous clusters with similar direction of meridional asymmetry in visual acuity. Preliminary data on the efficacy of treatment of amblyopia by accommodative facility training allows considering this training as a method of treatment for meridional amblyopia. The method of determination of meridional acuity should be included in the standard examination of patients with amblyopia.

IOL Power Calculation Features after Radial Keratotomy

IOL power calculation after keratorefractive surgery is an important applied aspect of cataract surgery. The probability of refractive error is especially high when calculating in patients with a history of radial keratotomy. There is no unified approach to the tactics and methodology of calculation for this category of patients at the moment. The studies were conducted in a group of 17 patients (26 eyes) with a history of RK. The Haigis formula, which does not use keratometry to predict ELP, was chosen as the main one for the calculation. IOL calculation and biometrics were carried out on the IOL-Master, but corrected TCP IOL (Ray Traced) data obtained on the Galilei keratotomograph were manually entered into the optional keratometry fields. Thу Burrett True-K and Hoffer Q were used as verification formulas, the calculation was also carried out on IOL-Master, using corrected Galilei data. In all cases, postoperative refraction close to emmetropic was obtained. The spherical component of refraction ranged from +0.5 to -1.0 D, cylindrical — from 0.0 to 4.0 D, according to autorefractometry. Visual acuity without correction ranged from 0.4 to 1.0. Uncorrected visual acuity of 0.8 and higher was obtained in 65.38% of cases. The calculation algorithm implemented by us using the Haigis formula in combination with the use of individually adjusted keratometric TCP IOL data (Ray Traced, Galilei), allowed us to significantly improve the accuracy of IOL power calculating in patients with a history of RK and achieve target refraction even in cases of complex and irregular corneal topography.

Коррекция астигматизма после сквозной кератопластики методом имплантации интрастромальных роговичных сегментов с применением фемтосекундного лазера

Purpose. Analysis of clinical and functional results of astigmatism correction after penetrating keratoplasty by intrastromal segment implantation (ICS) using a femtosecond laser (FSL). Material and methods. The clinical study included 22 patients (22 eyes) who were implanted ICS using FSL in order to correct postkeratoplastic astigmatism. Before surgery, uncorrected visual acuity (UCVA) averaged 0.09±0.05, best corrected visual acuity (BCVA) – 0.3±0.22, the value of the spherical component of refraction (SCR) – 1.16±3.98 D, cylindrical component of refraction (CCR) – –10.25±4.80 D, mean keratometry value (Kave) – 43.59±3.99 D, corneal hysteresis (CH) – 7.94±1.44 mm Hg, corneal resistance factor (CRF) – 7.01±1.81 mm Hg. Results. Intra- and postoperative complications were not observed. 12 months after the operation, the UCVA was 0.50±0.16, the BCVA – 0.60±0.18; SCR –1.05±3.18 D, CCR – –2.22±0.82D, Kave – 38.56±1.96 D, CH – 8.93±1.13 mm Hg, CRF – 8.44±1.44 mm Hg. Conclusion. The method of the intrastromal corneal segments implantation into a corneal graft using a femtosecond laser has demonstrated high refractive efficiency and safety in correcting postkeratoplastic astigmatism and increased the biomechanical properties of the corneal graft. Key words: induced astigmatism, intracorneal segments, femtosecond laser, keratoplasty

On refraction shift after trabeculectomy

To determine the factors affecting the shift of refraction after trabeculectomy. The study included 42 patients who were examined prior to trabeculectomy and at the following timepoints: 1 week, 1 month and 3 months after surgery. Examination included tonometry with assessment of corneal biomechanical properties, keratorefractometry with vector analysis, and biometry. The obtained data was processed for regression analysis and to find the possible correlations. All significant correlations between the measured parameters only occur on week 1. Postoperative spherical component of refraction (sphere) correlates negatively both with preoperative axial length (AL) and anterior chamber depth (ACD) (r=-0.699 and r=-0.458, p<0.05) and postoperative AL and ACD (r= -0.767 and r= -0.415, p<0.011). Dependence of sphere on AL is also expressed as a regression model. The magnitude of AL change depends on the magnitude of intraocular pressure (IOP) change (r=0.729, p<0.0001) and correlates negatively with postoperative IOP (r=-0.454, p=0.009) and baseline corneal hysteresis (CH; r= -0.482, p=0.009). Dependence of AL on IOP is also expressed as a regression model. The magnitudes of sphere and cylinder shifts correlate negatively with each other (r=-0.416, p=0.038). Keratometry reveals that the overall cylinder value correlates with the corneal cylinder, and so do the magnitudes of their shifts (r=0.589 and r=0.574, p<0.0001). Dependence of corneal hysteresis on IOP is expressed as a regression model; however, neither tonometric nor biomechanical corneal properties correlate with refraction. Sphere correlates negatively with AL and ACD. In turn, AL is related to the reduction in IOP. This dependence is likely the most important one for the refraction shift after trabeculectomy. No correlations were found for the change of astigmatism.

Long-term clinical and functional outcomes of high myopia correction by femtosecond laser-assisted implantation of an intrastromal ring

To analyze remote clinical and functional outcomes of correcting high myopia in patients with thin cornea by the method of femtosecond laser-assisted implantation of intracorneal implant MyoRing. The study included 22 patients (22 eyes; the mean age of study patients was 30.2±5.37 years). Mean spherical equivalent (SE) of refraction was -11.52±1.96 D, cylindrical component (cyl) of refraction was -2.04±1.64 D, minimal pachymetry index in the center was 491.6±20 µm, corneal hysteresis (CH) amounted to 8.6±1.19 mm Hg. The average pupil diameter in mesopic conditions was 5.6±0.23 mm. All patients had a history of mild amblyopia. The follow-up period lasted 2 years. Two years after the surgery uncorrected visual acuity was 0.6±1.22, corrected visual acuity 0.7±0.20. Mean spherical equivalent (SE) of refraction was 0.61±1.43 D, cylindrical component of refraction was -0.13±0.5 D. Predictability of SE within ±0.5 D was recorded in 84% of cases, ±1.0 - also in 84% of cases. Index of safety was 1.16, index of efficacy - 1.0. CH was 9.5±0.03 mm Hg. Mean pachymetry at the center did not change statistically significantly after the surgery in comparison to the initial data (p=1.00). MyoRing implantation is an effective and safe method, which ensures correction of the spherical component of refraction, as well as correction of astigmatism, improvement of biomechanical properties of the cornea, and an increase in corneal hysteresis (p=0.01).

Comparative evaluation of the results of one- and two-piece mushroom keratoplasty

To compare and evaluate the outcomes of one- and two-piece mushroom keratoplasty configurations for various corneal pathologies. A total of 32 patients (32 eyes) with corneal perforations, descemetocele and deep corneal opacities underwent surgery. Depending on the surgery technique, the patients were divided into 2 groups: group I (17 eyes) underwent manual one-piece mushroom keratoplasty according to our own technique; group II (15 eyes) underwent modified two-piece microkeratome-assisted mushroom keratoplasty according to the technique by M. Busin. All patients underwent clinical and functional studies before surgery and in the course of a 1-year follow-up. Transparent engraftment of the cornea was achieved in 82 and 80% of cases; best corrected visual acuity (BCVA) averaged 0.57±0.19 and 0.53±0.17; spherical component of refraction varied from 1.25 to +5.5 and from 1.25 to 6.0 diopters; mean corneal astigmatism was 3.15±1.73 and 3.21±1.89 diopters in groups I and II, respectively. At 6 months after surgery, the mean endothelial cell density (ECD) was 2336±198 and 2291±175 cells/mm2, at 1 year - 2041±189 and 1955±161 cells/mm2 in groups I and II, respectively. One- and two-piece mushroom keratoplasty is effective in surgical treatment of various corneal pathologies ensuring a high rate of transparent corneal engraftment. The revealed risk of false chambers formation between separate parts of the graft after the two-piece method could in most cases be eliminated by re-injecting air into the anterior eye chamber.

Peripheral refraction of myopic eyes with spectacle lenses correction and lens free emmetropes during accommodation

PurposeTo measure axial and off-axis refraction patterns in myopic eyes with spectacle lenses correction and lens free emmetropes in young healthy subjects at different target distances from 2.00 m (0.50 D) to 0.20 m (5.00 D) in terms of sphere, astigmatism, and spherical equivalent refraction.MethodsRefraction was measured at the center, 20 and 40 degrees from the line of sight both nasally and temporally in 15 emmetropic and 25 myopic young healthy subjects with an open field, binocular, infrared autorefractor (Grand Seiko WAM-5500, Hiroshima, Japan). Fixation target was a Maltese cross set at 2.00, 0.50, 0.33 and 0.20 m from the corneal plane. Changes in off-axis refraction with accommodation level were normalized with respect to distance axial values and compared between myopic eyes with spectacle lenses correction and lens free emmetropes.ResultsOff-axis refraction in myopic eyes with spectacle lenses correction was significantly more myopic in the temporal retina compared to lens free emmetropes except for the closest target distance. Relative off-axis refractive error changed significantly with accommodation when compared to axial refraction particularly in the myopic group. This change in the negative direction was due to changes in the spherical component of refraction that became more myopic relative to the center at the 0.20 m distance as the J0 component of astigmatism was significantly reduced in both emmetropes and myopes for the closest target.ConclusionAccommodation to very near targets (up to 0.20 m) makes the off-axis refraction of myopes wearing their spectacle correction similar to that of lens free emmetropes. A significant reduction in off-axis astigmatism was also observed for the 0.20 m distance.

Интрастромальная кератопластика с имплантацией роговичных сегментов как самостоятельный метод зрительной реабилитации у пациентов с кератоконусом

Purpose. To assess the possibility of using intrastromal keratoplasty with intracorneal ring segments implantation as an independent technique to achieve visual rehabilitation in patients with keratoconus of the stages I and II. Material and methods. There were examined and operated 14 eyes (10 patients) with keratoconus of the stages I and II (classification by Izmailova SB, 2014). Patients were divided into two groups depending on the keratoconus stage. All patients underwent intrastromal keratoplasty with intracorneal ring segments implantation using the femtosecond technology. The on average follow-up was 5.7 months. Results. In the first group: the average UCVA value increased with from 0.31±0.21 to 0.81±0.31 (p&lt;0.05); the BCVA increased from 0.89±0.08 to 0.94±0.10 (p&gt;0.05); the spherical component of refraction decreased from 0.96±1.25 to 0.08±0.20 (p&lt;0.05); the cylindrical component of refraction decreased from 4.25±1.73 to 0.50±1.22 (p&lt;0.05). In the second group: UCVA increased from 0.51±0.40 to 0.61±0.28 (p&lt;0.05); the BCVA increased from 0.70±0.17 to 0.81±0.26 (p&gt;0.05); the spherical component of refraction decreased from 4.88±2,61±0.53±0.63 (p&lt;0.05); the cylindrical component of refraction decreased from 2.69±1.65 to 1.41±1.02 (p&lt;0.05). Conclusion. 1. After implantation of intracorneal ring segments, both in patients with I and in patients with the II stage of keratoconus, there was an increase in the UCVA and BCVA, as well as a significant reduction in maximal keratometry and coma, which provides the improving of the quality of vision. 2. In all cases the UCVA and BCVA that were obtained after the treatment reached a sufficiently high level to ensure the possibility of performing their professional functions, without resorting to additional surgical treatment techniques. That characterizes this method as an independent and sufficient to achieve high visual acuity in patients with I and II stages of keratoconus. Key words: keratoconus, corneal intrastromal segments, femtosecond laser, visual rehabilitation.

Treating intrasurgical complications of corneal refractive operation with customized ablation. A clinical case

Purpose: to evaluate the prospects of customized Finalfit based ablation for optical rehabilitation of a patient with corneal surface errors caused by intrasurgical microtome-induced damage of a corneal flap during a LASIK excimer laser correction of vision.Material and methods. In Helmholtz Center, a patient with such damage was given a phototherapeutic keratectomy (PTK) combined with topographyguided photorefractive keratectomy.Results. In two months after the surgery, the patient’s uncorrected visual acuity rose from 0.15 to 1.0; the spherical component of refraction changed from -3.5 to +1.0 D, the cylindrical component of refraction fell from 1.75 to 0.25 D. Aberrometry demonstrated a decrease of RMS from 2.19 to 0.61 D, Total HOAs from 2.281 to 0.829; Tilt from 0.406 to 0.313; HOA from 1.152 to 0.247, Coma from 0.298 to 0.124, Trefoil from 1.088 to 0.094, SA from 0,127 to 0,021.Conclusion. The clinical case demonstrates the expediency and efficiency of corneal remodeling for the rehabilitation of induced errors of the corneal surface by excimer laser correction of vision based on PTK (Flex scan) + FinalFit after corneal refractive surgery.

Коррекция индуцированного астигматизма и сопутствующей миопии высокой степени методом имплантации кольца MyoRing с применением фемтосекундного лазера

Purpose. Analysis of the results of astigmatism correction after penetrating keratoplasty and concomitant high myopia using the MyoRing ring implantation, clinical case as an example. Material and methods. Patient G., 51 years old, underwent surgery to correct astigmatism and concomitant high myopia. MyoRing was implanted in the right eye within corneal transplant limits using femtosecond laser-assisted intrastromal MyoRing implantation. Before the surgery uncorrected visual acuity at the operated eye was 0.01; corrected visual acuity 0.06; spherical component of refraction was (–)6.0 D, cylindrical component was (–)8.0 D. Mean keratometry in the right eye was 43.96 D. Corneal hysteresis was 6.5 mm Hg, corneal resistance factor was 5.5 mm Hg, cornea thickness in center was 529 mkm. The patient was followed up for one year. Results. In 12 months after the surgery visual acuity of the right eye without correction was 0.7 and 0.8 with correction. Spherical component was (–)1.0 D, cylindrical component was (–)2.0 D. Mean keratometry in the right eye was 35.10 D. Corneal hysteresis was 7.2 mm Hg, corneal resistance factor was 6.3 mm Hg, cornea thickness in center was 533 mkm. The patient was satisfied with the result of operation. Conclusion. Femtosecond laser-assisted intrastromal MyoRing implantation for correction induced astigmatism after penetrating keratoplasty and concomitant high myopia is efficient, safe and provides strengthening of biomechanical properties of the cornea besides refractive and visual effect. Key words: postkeratoplastic astigmatism, high myopia, MyoRing, femtosecond laser

Keratorefractive Surgery for Residual Refractive Error Correction in Pseudophakic Patients

Purpose. Evaluation of the visual and refractive results of additional correction using LASIK and PRK methods in patients with residual refractive error after previous cataract surgery.Patients and methods.The prospective open study included 57 patients (79 eyes) who previously underwent cataract phacoemulsification (n = 37) or refractive lensectomy (n = 42) with various IOL models implantation (2012–2017). The average age of patients was 50.8 ± 13.9 (19–79) years. Operations LASIK (91.1 %) and PRK (8.9 %) were carried out according to standard methods. In 6 cases, femtosecond laser supported by laser correction. The target refraction ranged from –0.25 to 0.25 D in most (97.5 %) cases. The follow-up period ranged from 6 to 9 months.Results. The patients were divided into groups according to the type of residual refractive error (Group 1 — myopia, group II — emmetropia and group III — hyperopia). Statistically significant differences were determined for the species of previously implanted IOLs — in group II, the frequency of monofocal IOLs was significantly higher (p &lt; 0.05). In group II, the values of the cylindrical component of refraction were significantly higher compared with groups I and III (p &lt; 0.05). In group I, a significant (p &lt; 0.05) decrease in the spherical component of refraction from –1.36 ± 0.92 to –0.2 ± 0.8 D was observed. In patients of group II, there was a slight increase in the spherical component of refraction from 0 ± 0.20 to 0.25 ± 0.29 D (p &gt; 0.05). In group III, a significant (p &lt; 0.05) decrease was observed in the spherical component of refraction from 1.27 ± 0.69 to 0.43 ± 0.49 D. When analyzing the cylindrical component of refraction in group I, its decline was noted from –0.69 ± 0.5 to –0.38 ± 0.46 D (p &gt; 0.05). In group II, the largest decrease in the cylindrical component was observed from –1.6 ± 1.0 to 0.03 ± 1.10 Dptr (p &lt; 0.01). In all the studied groups, a statistically significant (p &lt; 0.05) increase in UCFVA was revealed in the postoperative period. Indicators K1 and K2 did not significantly change.Conclusion. The high efficiency of the correction using the LASIK, PRK and femtoLASIK methods on pseudophakic eyes with the achievement of the target refraction in most of the studied cases was shown. This method can be used as an alternative to spectacle and contact correction in patients with residual refractive error after cataract phacoemulsification and refractive lensectomy with IOL implantation.

One-piece mushroom keratoplasty outcomes

To clinically evaluate the results of one-piece mushroom-shaped keratoplasty. A total of 10 patients (10 eyes) were enrolled, all having corneal perforations and deep stromal opacities with involvement of Descemet's membrane. For transplantation, hypothermic preserved donor corneas with mean endothelial cell density of 2896±327 cells per 1 mm2 were used. Surgical technique. Recipient tissues as well as the graft were cut with the Moria trephine. For that, the 8.5-mm blade was replaced by a 6.5-mm one and vice versa, respectively, with attention paid not to violate the vacuum while making the cuts. Transparent cornea engraftment was achieved in all patients. Best corrected visual acuity averaged 0.55±0.22. Spherical component of refraction varied from -4.25 to +2.75 diopters. Mean corneal astigmatism was 3.35±1.73 diopters. At 6 months after surgery, the mean endothelial cell density was 2355±336 cells/mm2, at 1 year - 2141±304 cells/mm2. One-piece mushroom keratoplasty is an effective surgical treatment of corneal perforations and deep stromal opacities with involvement of Descemet's membrane that ensures a high rate of transparent corneal engraftment. The use of the Moria vacuum trephine in combination with blades of different diameters and secure fixation of the vacuum part of the trephine eliminate the risk of the 'mushroom stem' decentration relative to its 'head'.

Simultaneous topography-guided photorefractive keratectomy with accelerated collagen cross-linking in the treatment of stage I keratoconus

Purpose: to evaluate the efficiency of simultaneous topography-guided photorefractive keratectomy (PRK) with accelerated collagen cross-linking in the treatment of stage I keratoconus.Material and methods. 38 patients (49 eyes) aged 18 to 44 with stage I keratoconus were treated with simultaneous topography-guided PRK combined with accelerated corneal collagen crosslinking. Along with standard ophthalmological testing, patients underwent aberrometry, confocal microscopy, optical coherence tomography of the cornea, imaging of the anterior eye section on a Scheimpflug analyzer, and examination of the biomechanical properties of the cornea. The follow-up period was 2 years.Results. Two years after surgery, uncorrected visual acuity which originally was 0.23 ± 0.03 showed a statistically significant increase and reached 0.72 ± 0.02; best corrected visual acuity improved from 0.44 ± 0.03 to 0.89 ± 0.02; the refractive power of the cornea fell from 45.03 ± 0.28 to 42.55 ± 0.31 D; the spherical component of refraction reduced from -2.00 ± 0.19 to -0.73 ± 0.09 D; the cylinder component reduced from 2.46 ± 0.14 to 0.79 ± 0.07 mm, the thinnest point of the cornea reduced from 486.30 ± 4.78 to 406.80 ± 6.51 μm. The highest order aberrations showed the following results: Coma index reduced from 0.27 ± 0.12 to 0.08 ± 0.07, Tilt reduced from 0.53 ± 0.11 to 0.10 ± 0,09, and Trefoil reduced from 0.13 ± 0.04 to 0.05 ± 0.02.Conclusion. The analysis of clinical and functional results, biomechanical properties and structures of the cornea confirmed the efficacy and safety of the combined treatment of patients with stage I keratoconus.

Updated statistical analysis of higher order aberrations and total aberrations in patients with emmetropia and refractive anomalies

The authors performed a statistical analysis of the dependence of the total level of aberrations and the integral level of higher-order aberrations (hereafter, higher-order aberrations) depending on the type of clinical refraction and the degree of ametropia. The calculations made it possible to conclude that higher-order aberrations are characteristic of both eyes with emmetropia (“normal vision”) and eyes with ametropia (myopia and hyperopia). It turned out that the total level of eye aberrations in general directly correlates with the degree of ametropia and statistically significantly increases with an increase in the degree of ametropia (spherical component of refraction). Higher-order aberrations are practically unchanged in front of eyes with emmetropia and ametropia. According to updated data, the authors found that in the eyes with weak and moderate hypermetropia, the integral level of higher-order aberrations is higher than with myopia and emmetropia, but with a slight statistically significant difference.

The influence of a novel simulated learning environment upon student clinical subjective refraction performance: A pilot study

BackgroundOptometry students are taught the process of subjective refraction through lectures and laboratory‐based practicals before progressing to supervised clinical practice. Simulated leaning environments (SLEs) form part of an emerging technology used in a range of health disciplines; however, there is limited evidence regarding the effectiveness of clinical simulators as educational tools.MethodsForty optometry students (20 fourth year and 20 fifth year) were assessed twice by a qualified optometrist (two examinations separated by four to eight weeks), while completing a monocular non‐cycloplegic subjective refraction on the same patient with an unknown refractive error, simulated using contact lenses. Half of the students were granted access to an online simulated learning environment, The Brien Holden Vision Institute (BHVI) Virtual Refractor, and the remaining students formed a control group. The primary outcome measures at each visit were; accuracy of the clinical refraction compared to a qualified optometrist and relative to the Optometry Council of Australia and New Zealand (OCANZ) subjective refraction examination criteria. Secondary measures of interest included descriptors of student SLE engagement, student self‐reported confidence levels and correlations between performance in the simulated and real‐world clinical environment.ResultsEighty per cent of students in the intervention group interacted with the simulated learning environment (for an average of 100-minutes); however, there was no correlation between measures of student engagement with the BHVI Virtual Refractor and speed or accuracy of clinical subjective refractions. Fifth year students were typically more confident and refracted more accurately and more quickly than fourth year students. A year group by experimental group interaction (p = 0.03) was observed for accuracy of the spherical component of refraction and post hoc analysis revealed that less experienced students exhibited greater gains in clinical accuracy following exposure to the SLE intervention.ConclusionsShort‐term exposure to a SLE can positively influence clinical subjective refraction outcomes for less experienced optometry students and may be of benefit in increasing the skills of novice refractionists to levels appropriate for commencing supervised clinical interactions.

Predicting the necessity of LASIK enhancement after cataract surgery in patients with multifocal IOL implantation

PurposeTo investigate if the parameters measured routinely prior to cataract surgery with multifocal intraocular lens (IOL) implantation can predict the necessity of additional laser in situ keratomileusis (LASIK) to improve visual outcome.MethodsRecords of patients undergoing cataract surgery between January 2008 and December 2009 were reviewed. Individuals satisfied with visual outcome of cataract surgery and not satisfied were grouped (group 1 and 2, respectively). Preoperative data of refractive error, axial length, corneal astigmatism, intraocular pressure, and postoperative uncorrected visual acuity were recorded. Data was available for 62 patients (104 eyes), of which LASIK enhancement was deemed necessary in 21 eyes (20%; group 2). The receiver operator characteristic curves were used to discriminate between the groups and linear regression analysis was performed to predict the postoperative visual outcome.ResultsThe astigmatism measured preoperatively using manifest refraction had an accuracy of 64% in discriminating between the groups. Age, spherical component of refraction, axial length, corneal astigmatism, and intraocular pressure were very close to chance prediction 59%, 57%, 56%, 51%, and 51%, respectively. The postoperative uncorrected visual acuity had an accuracy of 79% in discriminating the groups. Individuals with uncorrected visual acuity worse than 20/40 after cataract surgery were most likely to undergo LASIK enhancement; however, approximately 20% of group 2 underwent LASIK enhancement despite having visual acuity of 20/30 or better. When combined, preoperative visual acuity accounted for just 7% of variance in postoperative uncorrected visual acuity.ConclusionRequirement of LASIK enhancement after cataract surgery with multifocal IOL implant is complex in nature, and parameters routinely measured before surgery cannot successfully identify the group requiring LASIK enhancement or predict postoperative uncorrected visual acuity.