Keratometry Readings Research Articles

Comparative study of anatomical and functional recovery of eye along with patient satisfaction score after small-incision cataract surgery and phacoemulsification cataract surgery.

Functional recovery after cataract surgery depends on the anatomical recovery of the eye. This study compared the improvement in visual function parameters after uniocular manual small-incision cataract surgery (MSICS) and phacoemulsification cataract surgery. This study included 310 patients divided randomly into two groups: 155 who received MSICS (MSICS group) and 155 who underwent phacoemulsification (phaco group) for cataract treatment. Outcome measures assessed included vertical and horizontal keratometry reading. The mean corneal astigmatism tear function measured using Schirmer 1 test results were recorded preoperatively, and on postoperative day 1, day 7, and day 30. Optical coherence tomography (OCT) was done to record the average central macular thickness (μm) on day 7 and day 30. The mean corneal astigmatism and anterior chamber inflammation were more in the MSICS group than in the phaco group immediately postoperatively. However, no statistically significant difference was found between the groups with respect to corneal sensation, mean corneal astigmatism, tear film function, and visual outcomes on postoperative day 30. Uncorrected visual acuity was better in the phacoemulsification group than in the manual SICS group on postoperative day 1, day 7, and day 30 (P < 0.001). Both phacoemulsification cataract surgery and manual small-incision sutureless cataract surgery (MSICS) are safe and effective for visual rehabilitation. Phacoemulsification is the preferred technique where resources are available with the advantages of less mean corneal astigmatism, less anterior chamber inflammation, and better uncorrected visual acuity (UCVA) in the immediate postoperative period.

Clinical Outcomes Comparison of Combined Small Incision Lenticule Extraction with Collagen Cross-Linking Versus Small Incision Lenticule Extraction Only.

Purpose To evaluate clinical outcome during 24 months follow-up between small incision lenticule extraction combined with cross-linking (SMILE Xtra) and small incision lenticule extraction (SMILE) only. Setting. Ophthalmology Division of San Rossore Medical Center, Pisa, Italy. Design Retrospective comparative case series. Methods The study comprised 70 eyes (35 patients); 40 eyes were corrected using SMILE and 30 eyes were corrected using SMILE Xtra using a low energy protocol. The outcomes were compared at 1, 6, 12, and 24 months postoperatively. Results The mean spherical equivalent (SEQ) reduced from −7.18 ± 1.21 D to −0.01 ± 0.09 D in the SMILE group and from −6.20 ± 2.99 D to −0.04 ± 0.1 D postoperatively in SMILE Xtra (p < 0.05). At 24 months the mean SEQs were −0.01 ± 0.24 D for SMILE and −0.15 ± 0.33 D for SMILE Xtra (p > 0.05). At 1, 6, 12, and 24 months, there were no statistically significant differences between the SMILE and SMILE Xtra groups in logarithm of the minimum angle of resolution (logMAR) uncorrected distance visual acuity (UDVA), safety, and efficacy index (p > 0.05). The mean average keratometry (K-avg) at 1, 6, 12, and 24 months after surgery did not shown any statistically significant difference between SMILE and SMILE Xtra group (p > 0.05). The mean maximum keratometry (K-max) readings at 1, 6, 12, and 24 months were not statistically significant between SMILE and SMILE Xtra group (p > 0.05). The preoperative mean thinnest point pachymetry (TTP) was 543.90 ± 22.85 μm in the SMILE group and 523.40 ± 37.01 μm in the SMILE Xtra group (p < 0.05). At 1, 6, 12, and 24 months the mean TTP was not statistically significant between the SMILE and SMILE Xtra groups (p > 0.05). At 24 months, the TTP was 408.29 ± 38.75 μm for the SMILE group and 402.22 ± 37 μm for the SMILE Xtra group (p > 0.05). In the preoperative period, the mean maximum posterior elevation (MPE) was 8.63 ± 4.35 μm for SMILE and 8.13 ± 2.54 μm for SMILE Xtra (p > 0.05). After the surgical procedure, both groups showed a statistically significant increase of the MPE (p < 0.05). At 24 months, the MPE was 11.00 ± 4.72 μm for SMILE Xtra and 10.14 ± 3.85 μm for the SMILE group (p > 0.05). In the preoperative period, the means of the root mean square (RMS) of high-order aberration (HOA) were 0.08 ± 0.03 μm for the SMILE group and 0.08 ± 0.03 μm for the SMILE Xtra group (p > 0.05). At 24 months, the RMS of HOA was 0.13 ± 0.07 μm for the SMILE group and 0.14 ± 0.07 μm for the SMILE Xtra group (p > 0.05). In the preoperative period, the root mean square of coma aberration (RMS-Coma) aberration was 0.06 ± 0.09 μm for the SMILE group and 0.04 ± 0.03 μm for the SMILE Xtra group (p > 0.05). At 24 months, the coma aberration of SMILE group was 0.12 ± 0.21 μm and 0.16 ± 0.25 μm for SMILE Xtra group (p > 0.05). Conclusions SMILE Xtra procedure is a safe and simple procedure that can be offered to patients with high corneal ectasia risk because there were no differences in the indices of ectasia compared to the group treated only with SMILE which has a low corneal ectatic risk.

One-year Visual and Refractive Outcomes of Deep Anterior Lamellar Keratoplasty (DALK) in Patients with Advanced Keratoconus.

To determine the one-year visual and refractive outcomes of deep anterior lamellar keratoplasty (DALK) in patients with advanced keratoconus (KC) using inexpensive readily available instruments. An observational study. Department of Cornea and Refractive Surgery, Al-Shifa Trust Eye Hospital, from November 2016 to March 2021. The authors evaluated different types of big bubble (BB) formation and the conversion rate of intended DALK (n=120) to the penetrating keratoplasty (PK) in patients with grade 4 KC. For analysis, only those patients were included in whom DALK was completed. Main outcome measures at 1-year follow-up were best-corrected visual acuity (BCVA), maximum keratometry (Kmax) reading, spherical equivalent (SE), and topographic astigmatism (TA). All the postoperative complications were recorded. Type 1 BB was formed in 68% (n=82) of the patients. An incomplete type 1 BB and type 2 BB were observed in twenty and eighteen patients, respectively. DALK was completed successfully in 102 patients. Whereas, the conversion rate to PK was 15% (n=18). The mean preoperative BCVA improved from 1.11±0.23 logMAR to 0.46±0.20 logMAR, at 1-year follow-up. The mean Kmax, SE, and TA readings reduced from a preoperative value of 62.1±4.60 D, -11.6±2.62 D, and 4.63±1.82 D, respectively, to 49.1±3.10 D, -5.65±0.84 D, and 2.78±1.35 D, respectively, at 1-year follow-up. Stromal rejection was recorded in two patients, but it responded well to topical therapy. Inexpensive readily available instruments can be used to perform DALK in patients with advanced KC with favourable visual and refractive outcomes. Big bubble, Deep anterior lamellar keratoplasty, Keratoconus, Perforation, Penetrating keratoplasty.

Continuous Intracorneal Ring Implantation in Keratoconus: Efficacy, Predictive Factors, and Complications.

PurposeTo examine the clinical outcomes, predictors of visual improvement and complications of continuous intracorneal ring (ICCR) implantation in patients with keratoconus and confirmed contact-lens intolerance (CLI).MethodsThis nonrandomized, multi-centric, retrospective cohort study examined visual, keratometric and clinical outcomes evaluated after a minimum follow-up of 2 months. Among the inclusion criteria for the standard treatment group (STG) were corrected distance visual acuity (CDVA) <20/25 Snellen, no central corneal scars, minimum corneal thickness >350µm, and central mean keratometry reading (meanK) <55 diopters. All other eyes were classified as non-standard treatment group.ResultsA total of 118 eyes of 118 patients with aged 32 ± 11 years were included in this study. At a median follow-up of 161 days (interquartile range: 111–372 days) ICCR implantation improved the CDVA from a mean of 0.38 to 0.15 logMAR (p<0.0001). Our correlation analysis showed lower preoperative CDVA to be the single best predictor of CDVA improvement, with eyes of a CDVA of 20/80 or lower improving by 4.3 ± 2.0 lines on average. Eyes with a meanK >55 diopters gained 9.04±4.83 lines in UDVA and 2.86±3.09 lines in CDVA. However, postoperatively these eyes had a CDVA of 0.32±0.21 logMAR which is significantly inferior to the STG outcome (p=0.001372). Fifteen eyes (12.7%) had to undergo a ring exchange procedure because of refractive under- (9 eyes) or overcorrection (6 eyes). Two eyes (1.7%) experienced medical complications.ConclusionThis study confirms the inclusion criteria of ICCR implantation in KC eyes with CDVA <20/25 and CLI. Particularly in eyes with a preoperative CDVA <20/80 and a meanK <55 diopters, ICCR implantation should be considered due to its reversibility and low rates of serious complications. The main challenge remains in the low predictability of the magnitude of this improvement in eyes with CDVA >20/30.

Snail Track Lesion with Flat Keratometry in Anterior Segment Dysgenesis Caused by a Novel FOXC1 Variant.

We report the phenotype of a 15-year-old female patient with anterior segment dysgenesis (ASD) caused by a novel heterozygous loss-of-function FOXC1 variant. The proband underwent an ophthalmic examination as well as a molecular genetic investigation comprising exome sequencing, a single nucleotide polymorphism array to access copy number and Sanger sequencing to exclude non-coding causal variants. There was bilateral mild iris hypoplasia with pupil deformation and iridocorneal adhesions. In addition to these features of ASD, the corneas were flat, with mean keratometry readings of 38.8 diopters in the right eye and 39.5 diopters in the left eye. There was a snail track lesion of the left cornea at the level of the Descemet membrane. The central corneal endothelial cell density was reduced bilaterally at 1964 and 1373 cells/mm2 in the right and left eyes, respectively. Molecular genetic analysis revealed that the proband was a carrier of a novel heterozygous frameshifting variant in FOXC1, c.605del p.(Pro202Argfs*113). Neither parent had this change, suggesting a de novo origin which was supported by paternity testing. We found no possibly pathogenic variants in the other genes associated with posterior corneal dystrophies or ASD. Further studies are warranted to verify whether there is a true association between snail track lesions, corneal flattening, and pathogenic variants in FOXC1.

Deciphering the enigma of astigmatism in cataract surgery

With about 87% of patients with cataracts having astigmatism, management of astigmatism in cataract surgery not only yields an improved unaided visual acuity and image quality but also higher patient satisfaction. The video will give a step-wise guide to cataract surgeons to manage astigmatism with cataracts. To hit the bull's eye as far as target refraction is concerned, it is necessary to understand the benefits and limitations of currently available cutting-edge technology and formulae and apply them to the cataract surgery practice. The purpose of the video is to make sure that we have no surprises in our Toric intraocular lens (IOL) planning. After a brief introduction to available modalities for the treatment of astigmatism, a step-wise approach to diagnostics is discussed, which will include the role of corneal topography and aberrometers and their application to planning Toric IOLs. Appropriate planning, implementation, and execution in form of preoperative and intraoperative pearls of using Toric IOLs are shown in the video. This will be followed by troubleshooting and case-based discussions and future perspectives including the possible role of corneal biomechanics. What this video adds new is the importance of topography, interpretation of Belin‒Ambrosio display map and the equivalent keratometry reading (EKR) map, aberrometry, and higher order aberration (HOA) analysis and role of biomechanics in Toric IOL planning. Video also highlights the importance of posterior corneal astigmatism and accurate axis marking. With a case-based approach and relevant examples, we are trying to decipher the enigma of astigmatism by giving a step-wise approach for the same. https://youtu.be/5VuEY_6NdQA.

Parental Keratoconus Literacy: A Socioeconomic Perspective.

PurposeTo assess the impact of parental socioeconomic status and keratoconus literacy on pediatric eye rubbing and keratoconus severity.MethodsIn this mixed-methods study, pediatric keratoconus patients (age ≤ 18 years) were retrospectively identified. Sociodemographic and clinical characteristics were extracted from the electronic medical record (EMR). Telephone surveys were subsequently conducted to assess parental keratoconus literacy, receipt of counseling on keratoconus prevention, eye rubbing, and household socioeconomic factors not available in the EMR. Parents reporting poor keratoconus literacy were probed via semi-structured interview to explore barriers to their understanding.ResultsForty-eight patients met inclusion criteria, 22 (46%) of whom were reached by telephone. Most patients were insured by Medicaid (73%) and current eye rubbers (82%). Few parents reported good or excellent keratoconus literacy now (32%) or at the time of diagnosis (18%). Parents with a high-school education, limited English proficiency, lower income level, and Medicaid insurance tended to have lower keratoconus literacy, though this was not statistically significant. Parental keratoconus literacy was not correlated with disease severity. High-school education, limited English proficiency, lower income level, and Medicaid insurance were correlated with steeper keratometry readings, which was statistically significant for high-school education. In-depth interviews revealed parents felt unconfident with eye health in general and perceived a personal responsibility for learning more.ConclusionThis is the first study exploring keratoconus literacy from a socioeconomic perspective, demonstrating lower literacy among socioeconomically marginalized parents and a tendency toward more severe disease in their children.

Retinal arcades in posterior microphthalmos: biometric correlation

ABSTRACT Clinical relevance Posterior microphthalmos (PM) is a rare developmental disorder characterised by high hyperopia, short axial length, presence of retinal papillomacular fold and relatively normal anterior segment findings. Background The purpose of the study was to compare the retinal arcade distance from fovea between PM cases and to correlate axial shortening in PM eyes with imaging findings. Methods This retrospective, comparative case series included 24 eyes of 12 patients with PM as cases and an equal number of age- and sex-matched controls. Retinal findings on optical coherence tomography (OCT), OCT-angiography, Multicolour® image, axial length and corneal biometry were computed, compared and correlated between two groups. Results Retinal papillomacular fold was noted in all 24 PM eyes. Retinal arcade narrowing was noted in PM (p < 0.001). The central retina (p < 0.001) and choroid (p = 0.003) was thick in PM. Corneal biometry showed shorter axial length (p < 0.001), high keratometry readings (p < 0.001) and small corneal diameters (p = 0.011) in PM. Vessel density (p = 0.031) on OCTA was denser and foveal avascular zone area (p = 0.033) reduced in PM. Strong negative correlation of axial length with spherical equivalent (r = > −0.804;p < 0.001), vessel density (r = > −0.803; p = <0.001) and K1 (r = > −0.76; p < 0.001) and K2 (r = > −0.67; p = 0.001) keratometry readings was noted in PM. Significant positive correlation was noted between axial length and anterior chamber depth (r = 0.75; p < 0.001), foveal avascular zone area (r = 0.56; p = 0.033) and corneal diameter (r = 0.65; p = 0.001). Vessel density on OCT-angiography correlated positively with central corneal thickness (r = 0.552;p = 0.005) and corneal powers K1 (r = 0.709; p = 0.001) and K2 (r = 0.56; p = 0.004) and negatively with corneal diameter (r = > −0.521; p = 0.033). Conclusion Increased choroidal thickening and retinal vascular arcade narrowing were two important, interesting observations noted with PM. Intercorrelation between the axial length, OCT, OCT-angiography and corneal biometry helped in understanding the pathogenesis and the structural and vascular changes in PM eyes.

Role of Ultrasound Biomicroscopy in Predicting Intraoperative Surgical Strategies in Penetrating Keratoplasty with Cataract Extraction and IOL Implantation

Background: Penetrating Keratoplasty with cataract extraction and Intraocular Lens (IOL) implantation (Triple procedure) is very challenging procedure because in cases of Opaque cornea, status of anterior segment is difficult to predict that can lead to intraoperative surprises. If not managed properly, these can severely affect visual outcome. To avoid this, we performed Ultrasound Biomicroscopy (UBM) preoperatively for detailed analysis of anterior segment structures and associated pathologies and later compared it with intraoperative findings to judge predictive accuracy of UBM in guiding surgical strategies, decision making and modifications intraoperatively. Methods and findings: 20 eyes of 20 patients with different grades of corneal opacities like simple corneal opacities (6 eyes) or adherent leucoma (7 eyes) or anterior staphyloma (7 eyes) that underwent Triple procedure (Penetrating Keratoplasty+ cataract extraction+ IOL implantation) were evaluated preoperatively by UBM and the findings were compared intraoperatively to find predictive accuracy of UBM. Extent and depth of corneal lesions, corneal thickness, anterior chamber depth, type, position and extent of synechiae, pupillary membrane and status of lens and capsule were assessed. Scan was performed to visualize any posterior segment pathology and to find Axial Length (AL). Keratometry readings of other eye were taken to calculate IOL power for implantation. Preoperative UBM findings when co-related intraoperatively was found to be accurate in 71.42%- 100% parameters and accordingly these cases underwent penetrating Keratoplasty with other modifications like Iridectomy, Membranectomy, Synechiolysis, iris reconstruction, Trabeculectomy, cataract extraction and IOL implantation. Conclusion: In cataract coexisting with corneal pathologies, UBM is Best and reliable guide in predicting and preplanning of surgical strategies for best visual outcomes.

Evaluation of the repeatability of optical coherence tomography in patients with age-related cataract associated with dry eye.

To assess the repeatability of a new optical biometer (OA-2000, Tomey, Japan) based on swept-source optical coherence tomography (SS-OCT) and Placido-disk topography in dry eyes with cataracts. A cross-sectional study was performed. Two hundred sixteen eyes of 216 cataract patients were enrolled in our hospital from March 2020 to December 2020. According to the subjective symptoms and objective examination of dry eye, the patients were assigned to dry eye group and non-dry eye group. Axial length (AL), keratometry readings (K), lens thickness (LT), anterior chamber depth (ACD), central corneal thickness (CCT) and white-to-white (WTW) distance were measured by one skilled operator. The repeatability of each parameter based on within-subject standard deviation (Sw), repeatability limit of standard deviation (2.77Sw), coefficient of variation (CoV) and intra-class correlation coefficient (ICC) was evaluated. There was no significant difference in age and gender between the two groups. NiaBUT and NifBUT in the dry eye group were significantly lower than those in the non-dry eye group (p < 0.05). The ICC mean values of AL, K1, K2, Km, ACD, LT and CCT were all greater than 0.960, except WTW. In the dry eye group, except CCT and WTW, the Sw scores for other biometric parameters were lower than 0.201, 2.77Sw scores were lower than 0.557, CoV(%) was less than 1%, and ICC mean values were greater than 0.964. Among them, the Sw scores for AL, LT and ACD were lower than 0.035, the 2.77Sw scores were lower than 0.097, and the ICC mean values are greater than 0.990. The ocular biological parameters measured by SS-OCT have good repeatability for age-related cataract patients with dry eyes, in which the AL, LT and ACD are the highest repeatable. However, more attention should be paid for WTW in clinical application since repeatability influence.

Current clinical practice in corneal crosslinking for treatment of progressive keratoconus in four Nordic countries.

To evaluate clinical practice in the diagnosis and treatment of progressive keratoconus with corneal crosslinking (CXL) in four Nordic countries. A questionnaire was sent to all centres at which keratoconus patients are evaluated and CXL is performed in Sweden, Denmark, Norway and Iceland. Nineteen of 20 centres participated. CXL is performed approximately 1300 times per year in these four Nordic countries with a population of around 21.7 million (2019). In most cases, progression is evaluated using the Pentacam HR, and the maximum keratometry reading (Kmax ) is considered the most important parameter. The most frequently used treatment protocol in Scandinavia is the 9mW/cm2 epi-off protocol, using hydroxylpropyl methylcellulose riboflavin (HPMC-riboflavin). The participants deemed the following areas to be in most need of improvement: adaptation of the CXL protocol to individual patients (5/19), the development of effective epi-on treatment protocols (4/19), optimal performance of CXL in thin corneas (4/19), improvement of the definition of progression (2/19), and diagnosis of the need for re-treatment (2/19). We concluded that the diagnosis of progressive keratoconus and the diagnostic equipment used are similar. Treatment strategies are also similar but are suitably different to provide an interesting basis for the comparison of treatment outcomes. The high degree of participation in this survey indicates the possibility of future scientific collaboration on CXL focusing on the areas deemed to need improvement. It would also be of interest to evaluate the possibility of creating a Nordic CXL Registry. The high number of CXL treatments performed ensures sufficient statistical power to solve many questions. Such a registry could be an important contribution to evidence-based care and would allow for longitudinal evaluation.

Intraocular lens power calculation in patients with irregular astigmatism.

Accurate intraocular lens (IOL) calculation in subjects with irregular astigmatism is challenging. This study evaluated the accuracy of using Scheimpflug-derived central 2-mm equivalent keratometry reading (EKR) values for IOL calculation in irregular astigmatism. This retrospective study included subjects (31 eyes of 30 patients) who underwent cataract surgery and IOL calculation using the 2-mm central EKR methods. We compared prediction error (PE) and absolute PE (APE) outcomes using SRK/T and Barrett Universal II formulas for keratometry data obtained from the IOLMaster 500 and Pentacam (anterior corneal sim k) devices. Cataract surgery and IOL calculation using the 2-mm central EKR methods resulted in improved visual acuity (uncorrected: from 1.13 ± 0.38 to 0.65 ± 0.46 logMar, p < 0.01; best-corrected: from 0.45 ± 0.24 to 0.26 ± 0.20 logMar, p < 0.01) after surgery. The percentage of subjects with best-corrected visual acuity of 6/6 was 22%, < 6/9 was 58%, and < 6/12 was 71%. For both the SRK/T and the Barrett formulas, the PE was similar to those obtained by IOLMaster (> 0.14) but lower than those obtained by the anterior corneal sim k (p < 0.02). IOLMaster provided keratometry reading in only 23/31 (74.1%) of cases. The use of Scheimpflug central 2-mm EKR for IOL calculation in irregular astigmatism was beneficial in terms of visual acuity improvement. It had comparable refractive prediction performance to the IOLMaster 500 and better than the anterior corneal sim K. The 2-mm EKR method can be used when IOLMaster cannot provide a reliable reading in abnormal corneas.

Changes in Visual Acuity and Keratometry Readings following Pterygium Excision: A Study in A Public Medical College Hospital

Introduction: Pterygium is a degenerative, triangular wing shaped, fibro vascular connective tissue of bulbar conjunctiva towards and onto the cornea, leading to significant astigmatism. It is a common ophthalmic condition of tropical and sub-tropical country like Bangladesh where there is dry sunny hot dusty climate.&#x0D; Purpose: To find out the change in visual acuity and keratomety before and after pterygium excision and effect of different grades of pterygium on the final outcome.&#x0D; Methods: This prospective study was carried out from March 2021 to December 2021 at Ophthalmolgy Department, Sher-E-Bangla Medical College &amp; Hospital, Barishal. Total 68 patients with different grades of pterygium were operated for pterygium excision with conjunctival autograft and were studied and analyzed. All the eyes underwent detailed ocular examination like visual acuity measured by Snellen’s chart; refractive astigmatism measured by automated keratometry and slit lamp biomicroscopy and fundus examination.&#x0D; Results: Pterygium is more common in males (61.76%) than females (38.23%) where 45.59% cases were in age group of 31-40 years followed by 33.82% in 41-50 years and rare (2.94%) in more than 60 years; so, 86.76% cases are in the age group of 31-60 years. Preoperatively mean±SD of K1 (Horizontal meridian) was 42.428±1.853 D and 3 month after the surgery it was 42.061±0.563 D. On the other hand mean±SD of K2 (vertical) readings before surgical excision were 44.185± 0.871 D and postoperatively after 3 months it was 42.691±0.384 D. Pre and post-operative BCVA in Grade I pterygium cases were 6/6-6/9 both pre &amp; post -operatively. In patients of Grade II preoperative VA was 6/18-6/36 which was postoperatively 6/12-6/18; in Grade III pre and postoperative VA was 6/24-6/36 and 6/12-6/18 respectively. While in Grade IV pterygium VA were 6/36-6/60 preoperatively and 6/18-6/24 postoperatively.&#x0D; Conclusion: We conclude that, the greater the grade of pterygium the lesser is the outcome of visual acuity after surgery; the greater was the change in keratometry reading. It was inferred that, timely and appropriate surgery at Grade II &amp; Grade III can result in not only a good visual outcome but also less complications.&#x0D; J. Natl. Inst. Ophthalmol. 2022; 5(2):25-30

Visual Outcomes of Microkeratome-Assisted Anterior Lamellar Keratoplasty in Keratoconus: 5-Year Results.

Purpose To report 5-year results of microkeratome-assisted anterior lamellar keratoplasty (MK-ALK) in cases of keratoconus. Methods Patients with advanced keratoconus and the thinnest corneal location 300 μ or more were recruited. A Carriazo–Barraquer microkeratome was used to remove a 200-μ cap from the recipient cornea, and to prepare a 300-μ anterior stromal graft from a donor cornea. A full-thickness crescentic incision was made in the posterior stromal recipient bed using a 6.5-mm suction trephine. The donor was sutured to the recipient bed using interrupted nylon sutures. The minimum follow-up was five years. Results Twelve eyes of 12 patients were included. The mean age was 26 ± 8 years. None of the patients required conversion to penetrating keratoplasty. Mean logMAR uncorrected and best spectacle-corrected visual acuity, respectively, improved from 1.56 ± 0.24 and 1.18 ± 0.32 preoperatively, to 0.63 ± 0.38 and 0.18 ± 0.12, five years after surgery (P=0.001for both). There was also a statistically significant reduction of mean manifest spherical equivalent, refractive cylinder, and mean keratometry readings. Posterior stromal striations occurred in all patients immediately after surgery but resolved after a maximum of 3 months. At five-years, anterior segment optical coherence tomography revealed a clear interface in all cases and a mean graft thickness of 328 ± 27 μ. Conclusion MK-ALK is a safe and effective procedure for advanced keratoconus. Where feasible, it may be the best choice for patients at high risk of poor outcomes with penetrating keratoplasty, such as young patients with atopic keratoconjunctivitis or Down's syndrome.

Angle κ Measurement and Its Correlation with Other Ocular Parameters in Normal Population by a New Imaging Modality.

This study obtained normative database for angle κ using Orbscan 3. The average angle κ values were 2.3 ± 1.34° in the whole sample, 2.23 ± 1.36° in myopic eyes, and 3.3 ±1.5° in hyperopic eyes. This is very important to optimize refractive surgery outcomes. The aim of this cross-sectional study was to obtain the value of mean angle κ in normal eyes of patients seeking laser vision correction, by the Orbscan 3. The study was conducted on healthy eyes of people seeking laser refractive surgery. A total of 1815 eyes of 908 candidates were included. These were examined as a part of pre-operative assessment. Orbscan 3 was used to measure angle κ and its XY intercepts, keratometry readings, central corneal thickness, thinnest location, white-to-white diameter, and corneal asphericity of front surface (Qf) and back surface (Qb). The mean ± standard deviation angle κ in all eyes was 2.3 ± 1.34°. The values were 2.23 ± 1.36° in myopic eyes, 3.3 ±1.5° in hyperopic eyes, and 2.9 ±1.6° in emmetropic eyes. Positive correlation was found between angle κ and age, spherical equivalent, subjective sphere, and white-to-white diameter. On the other hand, axial length, average keratometry, central corneal thickness, pupil diameter, and asphericity Q front were negatively correlated with angle κ. The mean ± standard deviation angle κ value measured by the Orbscan 3 was 2.3 ± 1.34°. This could be attributed to different software used, in addition to the relatively high axial length in the studied eyes.

Preliminary demonstration of a novel intraocular lens power calculation: the O formula.

To evaluate the performance of a new formula of intraocular lens (IOL) power calculation (the O formula) based on ray tracing without commonly used parameters, including ultrasound-compatible axial length, keratometry readings, and A-constant. Tokyo Medical Center, Tokyo, Japan. Retrospective consecutive case series. 423 eyes (423 patients) implanted with a single-piece, L-loop, acrylic IOL were enrolled. All biometric data for the O formula were obtained by anterior segment swept-source optical coherence tomography (SS-OCT) and SS-OCT-based biometer. The performance of the O formula was compared with those of the Barrett Universal II (BUII) and Kane formulas at 1 month postoperatively. Statistical analysis was applied according to a heteroscedastic test with SD of prediction errors as the main parameter for formula performance. The SD of the O formula (0.426) was statistically significantly lower than that of the BUII formula (0.464, P = .034) but not statistically significantly different from that of the Kane formula (0.433, P = .601). The percentages of patients with refractive prediction errors within ±0.50 diopter (D) and ±1.00 D of the O, BUII, and Kane formulas were 75.4% and 98.6%, 77.1% and 97.9%, and 76.6% and 98.1%, respectively. The O formula, based on ray tracing using SS-OCT-based devices, is one of the promising approaches for IOL power calculation, although additional larger scale studies are needed. It may be used as an alternative in IOL power calculation because of its independence from commonly used parameters.

Changes in Astigmatism and Visual Acuity after Pterygium Excision in the Ashanti Region of Ghana

Background: Pterygium is a conjunctival subepithelial fibrovascular growth commonly occurring in the inter-palpebral conjunctiva nasally or temporally. It tends to grow over the cornea, leading to visual impairment due to various factors, including astigmatism.&#x0D; Methods: This was a prospective, multi-centered, hospital-based, interventional study carried out within 12 months in three eye centers in the Ashanti region of Ghana. One hundred eyes of 100 adults (≥18 years) with primary pterygia were recruited. Operated eyes had measurements of uncorrected visual acuity (UVA), aided visual acuity (AVA), and keratometry readings (K-readings) before pterygium excision with conjunctival autograft (CAG), 2 weeks after surgery, and 6 weeks after surgery.&#x0D; Results: The mean age of patients was 47.1±11.5 years. The mean pre-operative astigmatism was 5.0±5.9 D. The mean astigmatism values at 2 and 6 weeks post-operatively were 1.7±1.5 and 1.3±1.0 D, respectively. Eighty-nine eyes had AVA ≥6/12 (0.11 mean logMAR) before surgery, whereas 97 eyes had AVA ≥6/12 (0.02 mean logMAR) 6 weeks after surgery, and the increase was statistically significant.&#x0D; Conclusion: Pterygia excision with CAG leads to an approximately fourfold reduction in mean pterygium-induced astigmatism by 6 weeks after surgery.

The repeatability and agreement of biometric measurements by dual Scheimpflug device with integrated optical biometer

To determine the repeatability of biometric measurements by dual Scheimpflug Devices with Integrated Optical Biometers and its agreement with partial coherence interferometry according to the axial length (AL), and the presence of cataracts. The present population-based cross-sectional study was conducted on the geriatric population in Tehran. For participants, imaging was performed by dual Scheimpflug Devices with Integrated Optical Biometers (Galilei G6) and partial coherence interferometry (IOL Master 500). All measurements were performed by one person. In both normal and cataractous eyes, the ICC values were above 0.99 for three measurements of AL, intraocular lens (IOL) power target, anterior chamber depth (ACD), central corneal thickness (CCT), flat and steep keratometry readings, and mean total corneal power (MTCP). The repeatability coefficient for the AL measurements was 0.003 and 0.002 in eyes with and without cataracts, respectively. The mean difference of AL between IOL Master 500 and Galilei G6 in normal and cataractous eyes was 0.015 and −0.003 mm, respectively. The 95% limits of agreement (LoA) of AL between these two devices were −0.09 to 0.12 mm in normal and −0.09 to 0.08 mm in cataractous eyes. The 95% LoA of ACD between the two devices was −0.13 to 0.36 mm and −0.10 to 0.31 mm in eyes without and with cataracts, respectively. The 95% LoA of steep K between the two devices was −0.63 to 0.32 and −1.04 to 0.89 diopter in normal and cataractous eyes, respectively. The results of the present study indicate the high repeatability of Galilei G6 in ocular biometric measurements. Galilei biometric measurements, had a very high agreement with the IOL Master 500.

Accelerated corneal crosslinking causes pseudoprogression in keratoconus within the first 6 weeks without affecting posterior corneal curvature.

To evaluate the effectiveness of epithelium-off (epi-off) accelerated corneal crosslinking (A-CXL, 9 mW/cm2, 10 min) in adult keratoconus (KC) patients. The study included 151 KC corneas (124 patients) after A-CXL. The parameters best corrected visual acuity (BCVA) and the tomographic readings (Pentacam HR, Oculus, Germany) were analysed at 24, 12 and 6 months preoperatively, prior to surgery; and 6 weeks, 6 months, 1, 2 and >2 years postoperatively. The demarcation line was assessed by anterior segment optical coherence tomography (Tomey SS-1000, CASIA 2 (Tomey, Nagoya, Japan)). Comparing pre- to postoperative findings 6 weeks after A-CXL with paired t-test, the anterior steep (46.8 ± 4.0|47.1 ± 4.1), flat (50.2 ± 4.3|50.6 ± 4.6) and maximal keratometry (57.6 ± 6.8|58.3 ± 6.8) increased (p < 0.05), while the thinnest pachymetry decreased significantly (459 ± 39|444 ± 42, p < 0.05). Lateron, however, there was a decreasing anterior flat (1, 2 and >2 years; p < 0.0001), mean (1 year; p = 0.01 and 2 years; p = 0.03) and maximal keratometry (1, 2 and >2 years; p < 0.0001). The posterior corneal keratometry readings did not change significantly until >2 years after A-CXL (MANOVA; steep, p = 0.008; flat, p = 0.027; mean, p = 0.007). The mean depth of the demarcation line was 242 ± 62 µm (53.6%). The preoperative logMAR BCVA (0.35 ± 0.02) decreased 6 weeks after A-CXL (0.39 ± 0.03) followed by a continuous improvement until the latest follow-up (0.18 ± 0.04). A-CXL constitutes a successful method for KC stabilization. Signs of KC progression occur within the first 6 weeks postoperatively ("pseudoprogression"), but this is not indicative of the long-term effect.

Outcomes of a Single-Segment Intrastromal Corneal Ring in Early Keratoconus and Early Pellucid Marginal Degeneration.

To determine the effect of a single-segment intrastromal corneal ring segment (ICRS; Intacs SK) on early keratoconus (KCN) and pellucid marginal degeneration (PMD). It is a prospective interventional study. One hundred twenty-four eyes (99 patients) with KCN and 36 eyes (26 patients) with PMD at early stage (the maximum keratometric reading less than 55 diopters) were included to ICRS implantation using femtosecond laser at a tertiary university-based hospital and a private outpatient center. The uncorrected distance and spectacle-corrected visual acuity (UDVA and SCDVA), manifest spherical and cylindrical refractions, and keratometry indices were measured preoperatively and postoperatively, 1week, 2 and 6months. One week after surgery, significant improvements were observed in UDVA, SCDVA, cylinder and keratometry readings of both KCN and PMD groups (all P < 0.05) with no significant changes afterward. No significant change occurred in the sphere refraction of PMD group (P = 0.10) in contrast to KCN group (P < 0.001). Corneal irregularity of KCN group in central 3 and 5mm zones increased at 1week (both P < 0.001) and then started to decrease up to 6months. However, the corneal irregularity of PMD group had significant reduction only at 1week in 5-mm zone (P = 0.02) and 2months in 3-mm zone (P = 0.01) postoperatively. The final efficacy indexes were 1.44 ± 0.71 and 0.87 ± 0.40 in KCN and PMD groups, respectively. Visual acuity, refractive errors and keratometry values have been improved after one-segment Intacs SK implantation in early KCN and PMD patients.