Lens Fitting Research Articles

Affluence and Contact Lens Prescribing.

To assess the impact of national affluence on the extent of prescribing of various types of soft contact lenses. Using information derived from a large bank of contact lens prescribing data, the relationship between the percentage prescribing of daily disposable, toric, silicone hydrogel, and multifocal contact lenses versus the gross domestic product at purchasing parity per capita (GDP [PPP]) was determined for all countries in which contact lens prescribers returned survey forms relating to greater than 100 contact lens fits between 2017 and 2021, inclusive. Data from 39 countries were analyzed, comprising 94,181 contact lens fits. The relationship between percentage contact lens prescribing versus GDP (PPP) was highly statistically significant for daily disposable lenses (r 2 =0.35, P <0.0001), marginally significant for toric lenses (r 2 =0.08, P =0.06), and not significant for silicone hydrogel lenses (r 2 =0.01, P =0.42) or multifocal lenses (r 2 =0.02, P =0.35). The rate of prescribing daily disposable contact lenses, and to a lesser extent toric lenses, is related to national affluence. The contact lens industry, practitioners, and governments/regulatory bodies should remain cognizant of this association and, where possible, reduce cost barriers to the purchase of such contact lens products so that they can be prescribed based on important clinical, refraction, and lifestyle considerations.

Daily Variations of Corneal White-to-White Diameter Measured with Different Methods.

PurposeA precise determination of the corneal diameter is essential for the diagnosis of various ocular diseases, cataract and refractive surgery as well as for the selection and fitting of contact lenses. The aim of this study was to investigate the agreement between two automatic and one manual method for corneal diameter determination and to evaluate possible diurnal variations in corneal diameter.Patients and MethodsHorizontal white-to-white corneal diameter of 20 volunteers was measured at three different fixed times of a day with three methods: Scheimpflug method (Pentacam HR, Oculus), placido based topography (Keratograph 5M, Oculus) and manual method using an image analysis software at a slitlamp (BQ900, Haag-Streit).ResultsThe two-factorial analysis of variance could not show a significant effect of the different instruments (p = 0.117), the different time points (p = 0.506) and the interaction between instrument and time point (p = 0.182). Very good repeatability (intraclass correlation coefficient ICC, quartile coefficient of dispersion QCD) was found for all three devices. However, manual slitlamp measurements showed a higher QCD than the automatic measurements with the Keratograph 5M and the Pentacam HR at all measurement times.ConclusionThe manual and automated methods used in the study to determine corneal diameter showed good agreement and repeatability. No significant diurnal variations of corneal diameter were observed during the period of time studied.

Managing a middle-aged patient with bilateral neglected keratoconus

The Orbscan's benefits include providing a thickness map and being noncontact for keratoconus screening. However, several developing countries have delayed keratoconus management due to a lack of resources and qualified examiners. Here we report a case of underdiagnosed and mistreated by high astigmatism, leading to a neglected case of keratoconus. A 34-year-old woman is bothered by her developing blurred eyesight and habit of scratching her eyes. The streak retinoscopy examination revealed the right eye was 5/20 cc S+7.75 C-6.00 Axis 150 became 5/15 and 5/20 cc S+7.25 C-6.00 Axis 80 became 5/15 for the left eye. The Placido test revealed irregular lines. The Schirmer test showed dry eyes. Slit-lamp examination revealed irregular thin cornea, Munson sign, Rizzuti's sign, and Vogt's striae were positive. The manual keratometer showed remarkably high corneal powers. The corneal topography showed characteristics of keratoconus. Scleral contacts with AS-OCT guiding were inserted into both eyes. Each eye's final BCVA improved to 5/12 and 5/6.5, respectively. The patient attained better visual performance and comfort. Detecting keratoconus by corneal topography and scleral contact lens fitting improved visual acuity. A skillful practitioner and accessible sources are essential to prevent these neglected cases.

Intrastromal corneal ring segments followed by PRK for postkeratoplasty high astigmatism: prospective study.

To evaluate refractive and topographic results of the association of intrastromal corneal ring segments (ICRS) with photorefractive keratectomy (PRK) for the correction of high (>6.0 diopters [D]) postkeratoplasty astigmatism (PKA). University of São Paulo, São Paulo, Brazil. Prospective interventional study. Postpenetrating keratoplasty patients, intolerant to contact lens fitting, and with corneal astigmatism higher than 6.0 D were treated by the combination of ICRS and PRK from January 2017 to June 2019. First, patients underwent femtosecond laser-assisted ICRS implantation to reduce and regularize corneal astigmatism, and 3 months later, submitted to PRK for the residual astigmatism. Outcomes were obtained 12 months after PRK. The study comprised 30 eyes of 29 patients. Mean uncorrected distance visual acuity (logMAR) changed from 1.16 ± 0.37 in the preoperative to 0.69 ± 0.40 after ICRS ( P < .0001) and to 0.34 ± 0.29 12 months after PRK ( P < .0001). Mean spherical equivalent decreased from -5.19 ± 4.81 D in the preoperative to -3.38 ± 4.51 D after ICRS ( P < .0001) and to -2.30 ± 2.84 D after PRK ( P = .132). Mean topographic astigmatism decreased from 7.88 ± 2.13 D in the preoperative to 5.47 ± 2.29 D after ICRS ( P < .0001) and to 4.12 ± 2.93 D after PRK ( P = .003). Mean refractive astigmatism decreased from 7.10 ± 1.13 D in the preoperative to 4.61 ± 1.61 D after ICRS ( P < .0001) and to 2.58 ± 1.49 D after PRK ( P < .0001). After PRK, the mean correction index (CI) for corneal astigmatism was 0.77 ± 0.36. The ICRS/PRK combination resulted in a higher CI than ICRS only, both for corneal and refractive astigmatism. 2 eyes (8%) presented clinically significant opacification. Other complications were endothelial rejection (n = 1, 4%), infectious keratitis (n = 1, 4%), and ICRS extrusion after corneal melting (n = 1, 4%). The association of ICRS and PRK was effective for treating high PKA. This strategy improved visual acuity, spherical equivalent, topographic and refractive astigmatism and resulted in a high CI. Safety questions remain open and must be balanced against benefits.

Synthesis of isognostic text images for visual performance evaluation

Subject of study. Principles and technologies for synthesis of test letter charts and standardization of measurements of reading parameters for evaluation of visual performance in the reading process, which is the most important type of human visual activity, are the subjects of the study. Aim of study. The study was aimed at developing a synthesis algorithm for textual isognostic images for quantitatively evaluating reading parameters as indicators of the state of visual performance that ensure the correlation between optical and semantic properties based on optical and optometric standards. Methods of study. A set of test images in the form of texts was created using digital methods for image synthesis. The text images were standardized for measuring reading parameters using optometric methods. Main results. A set of texts was synthesized and standardized considering the complexity and number of symbols in words, the frequency of occurrence and average width of Russian letters, the lengths of sentences, the angular sizes of characters, and the contrast. The text was standardized according to the angular visual acuity and conventional optometric standard ISO 8596, 2009. The synthesized test images comprised sets of text fragments of similar numbers of characters but different angular sizes. The sizes of the characters were correlated with the threshold angular values characterizing visual acuity according to optometric standards. The maximum reading speed, critical print size, and reading acuity were measured in 29 healthy adult test subjects to assess the reproducibility of results obtained using the synthesized test images. The measurements were performed twice for each test subject using two different charts synthesized using the developed method. No statistically significant difference was observed between the measurement results, which indicated good reproducibility of the results obtained using this test. Practical significance. The proposed algorithm for synthesis of standardized texts for assessing reading parameters is the simplest general method for a broad application in routine effectiveness evaluation of the therapy of macular zone pathology and lens fitting for short working distances.

Paediatric Contact Lens Fitting During COVID-19

The COVID-19 pandemic which has swept the world since the start of 2020 is impacting day to day lives including contact lens wear too. Though the number of cases and deaths is growing continuously, the researchers have found no relationship between the contact lens use and COVID infection. There are specific eye disorders in children who require contact lens fitting rather than dispensing spectacles which include monocular paediatric aphakia, irregular astigmatism, anisometropia, unilateral ametropia, post trauma, aniridia, albinism, high refractive errors etc. So COVID-19 should not be a hindering factor for the fitting and assessment of contact lenses in children as till now SARS-CoV-2 viruses are rarely found in the tears of patients who have tested positive for the disease.

Benefits of Scleral Lens in the Management of Irregular Corneas and Dry Eye Syndrome After Refractive Surgery.

To evaluate the utility of the SPOT scleral lens (Oxygen Permeable Scleral Lens of Thonon; LAO, Thonon-les-Bains, France) in the management of the irregular cornea after refractive surgery. We included 19 patients (35 eyes) with irregular corneas after refractive surgery. Patients were fitted with scleral lenses after the failure of conventional contact lenses adaptation. The ophthalmologic examination included measurement of best-corrected visual acuity (BCVA), slitlamp examination, and evaluation of ocular aberrations (Objective Scattering Index [OSI] and higher-order aberration [HOA]). Scleral lens fitting increases significantly the BCVA from 0.33 (±0.25) to 0.08 (±0.13) LogMAR (P<0.001). There was also a significant decrease in Ocular Surface Disease Index from 66.2±22.8 to 42.4±18.9 (P<0.001). Ocular aberrations (OAs) are also significantly reduced by the scleral lenses, the mean OSI goes from 7.2 (±4.2) to 3.0 (±1.8) (P<0.001), OA from 2.58 (±1.34) to 1.98 μm (±2.31) (P=0.035), and HOA from 0.94 (±0.51) to 0.48 (±0.23) (P=0.0018). Fitting with scleral lenses improves patients' optical and ocular surface problems. Scleral lens restores BCVA and the quality of life. Fitting with scleral lenses is an alternative to further surgery on these fragile eyes and is sometimes the only viable treatment option for the patient.

Results of the Pinhole Test Correlate with Hybrid Contact Lens Visual Acuity in Patients with Visual Impairment due to Corneal Diseases.

Introduction Trial rigid lens fitting is considered the best approach to determine whether the correction of residual defocus and irregular astigmatism might improve the visual acuity in patients with corneal disorders including keratoconus. This study aimed to analyze the correlation between hybrid lenses and pinhole visual acuity (VA). Methods Patients undergoing hybrid contact lens fitting at the Hygeia Clinic, Poland, were included. The VA of each patient was assessed as decimal Snellen fractions under the following conditions: (i) uncorrected VA, (ii) VA with spherocylindrical correction (i.e., corrected distance VA), (iii) VA with a single 1.2 mm pinhole occluder, and (iv) VA with the best-fitted hybrid contact lens. Pearson's correlation coefficient r was used to assess correlations among variables. Results This study involved 29 eyes of 19 patients, mainly with advanced keratoconus. The uncorrected VA was 0.11 ± 0.10. The pinhole test provided significantly improved VA over corrected distance VA (0.51 ± 0.29 vs. 0.31 ± 0.20, respectively; p < 0.0001). Similarly, the fitted hybrid contact lenses provided improved VA over corrected distance VA (0.66 ± 0.26 vs. 0.31 ± 0.20, respectively; p < 0.0001). The pinhole VA was strongly correlated with the hybrid contact lens VA (r = 0.8135; 95% CI: 0.61–0.92; p < 0.0001). The improvement in the pinhole test over corrected distance VA was moderately correlated with the improvement with the fitted lens over corrected distance VA (r = 0.6269; 95% confidence interval (CI): 0.32–0.80; p=0.0005). Conclusions A significant improvement in VA with the pinhole test is a simple predictor of general improvement with hybrid contact lenses. The pinhole test should be used in patients with corneal diseases such as keratoconus to determine whether optical aberrations associated with the disease cause their visual impairment.

Эффективность зрительной реабилитации пациентов с использованием склеральных линз после кератопластики

Objective. To analyze the efficacy and safety of SCL in patients after keratoplasty, both penetrating and layer-by-layer, and other concomitant conditions. Methods. The study included 114 patients (144 eyes) after keratoplasty (78 men and 27 women) aged 39.18 years (range, 18 to 75 years). In 23 cases fitting of SCL was refused. For the remaining 127 eyes, SCLs from the SkyOptix laboratory were selected according to the standard method. Scleral lenses were adapted in 127 eyes (100 patients): 81 patient in one eye and 23 patients in both. The average age of the corneal graft is from 1.7 to 32 years (11.2±11.4 years). Results. After fitting of scleral lenses in all patients visual acuity in the lens averaged 0.9±0.03, that is, it has increased compared to the maximum corrected visual acuity before fitting. It follows from the study that in the vast majority of patients with corneal scarring, the type of optimal lens design was Oblate (89.6 %). Conclusions. Scleral lenses can be successfully used for visual rehabilitation in patients after various types of keratoplasty, both penetrating and layered, as well as in other surgical interventions on the graft. Key words: scleral contact lenses; visual rehabilitation; keratoplasty.

Comparison of Javal-Schiøtz keratometer, Orbscan IIz and Pentacam topographers in evaluating anterior corneal topography

ABSTRACT Clinical relevance Inter-instrument variation in anterior corneal shape (ACS) measurement has a consequence for ocular clinical practice. Background To consider inter-instrument variability in keratometry measurements across the ACS and to explore instrument protocols for determining ACS keratometric analogues (KAs). Methods Mean keratometry/KAs of the right eye were recorded using Javal-Schiøtz keratometer (J-S), Orbscan IIz and Pentacam from 124 subjects (78 females; mean ± SD age: 24.71 ± 6.61 years). Mean radii of curvature were obtained for 1-mm wide annular zones extending up to 6 mm (horizontally) and 4 mm (vertically) from the apex for Orbscan and Pentacam. Zonal mean radius of curvature was calculated by averaging keratometry values for all measured points within the zone. Results KA (mean ± SD): Horizontal: Orbscan (7.80 ± 0.31 mm) and J-S (7.82 ± 0.29 mm) were not significantly different (p = 0.072). Pentacam (7.86 ± 0.29 mm) was significantly flatter than J-S (p < 0.001) and Orbscan (p < 0.001). Vertical: Orbscan (7.64 ± 0.31 mm) was significantly steeper than J-S (7.67 ± 0.29 mm, p < 0.005) and Pentacam (7.70 ± 0.29 mm, p < 0.001). Pentacam was significantly flatter than J-S (p < 0.001) and significant flatter than Orbscan across the entire profile (1-4 mm zones horizontal and vertical, p < 0.001). LoAs (CI): J-S/Orbscan: ±0.75 mm (0.05–0.18); J-S/Pentacam: ±0.72 mm (0.01–0.12); Pentacam/Orbscan: ±0.16 mm (0.04–0.08). There was a +0.03 mm positive bias for Orbscan compared to J-S, +0.06 mm positive bias for Orbscan compared to Pentacam and −0.03 mm negative bias for Pentacam compared to J-S. Conclusions Algorithms used by Orbscan and Pentacam to solve the peripheral paraxial ray problem produce significantly different KAs. Instrument-specific KAs cannot be used inter-changeably between instruments. Differences in KA between instruments are not significant for ocular surgery, but may influence rigid contact lens fitting. Pentacam measures flatter than Orbscan and J-S.

Associations Between Lid Wiper Microvascular Responses, Lens Fit, and Comfort After One Day of Contact Lens Adaptation by Neophytes.

To determine associations between lid wiper microvascular responses, lens fit, and comfort after 1 day of contact lens adaptation by neophytes. Functional slitlamp biomicroscopy was used to image the microvascular network of the upper tarsal conjunctiva, lid wiper, and bulbar conjunctiva. Fractal dimension was obtained to represent vessel density. Ultra-high-resolution optical coherence tomography was used to image the lens edge and fitting characteristics, including lens movement and lens-induced conjunctival indentation. Ocular comfort was rated using a 50-point visual analogue scale (VAS). Forty-nine healthy subjects without a history of contact lens wear were recruited. A contact lens was then fitted in the right eye. Imaging was taken at baseline and 6 hr after lens wear. The changes of VAS comfort score were negatively related to the changes of the vessel density in the lid-wiper (R 2 =0.18, P =0.002) and bulbar conjunctiva (R 2 =0.13, P =0.009). However, the changes of VAS were positively related to the changes in vessel density of the tarsal conjunctiva (R 2 =0.11, P =0.02). The changes of ocular microvasculature were not related to the objective metrics of the lens-fitting characteristics ( P >0.05). Similarly, the changes in the VAS comfort score were not related to the objective metrics of the lens-fitting characteristics ( P >0.05). Contact lens discomfort seemed to relate to lid wiper microvascular responses rather than fitting characteristics after 1 day of contact lens adaptation by neophytes.

Changes in corneal thickness, corneal volume, and densitometry after long-term orthokeratology wear

PurposeTo investigate changes in the corneal volume, corneal densitometry and pachymetry of young myopes wearing over-night orthokeratology (OK) contact lenses. MethodsThe medical records of 28 right eyes of young myopes wearing OK between 2013 and 2018 were reviewed retrospectively. The baseline refractive error, best corrected visual acuities at baseline and uncorrected visual acuity at the most recent visit were recorded. Corneal volume of the central 10 mm cornea; densitometry at central, nasal and temporal cornea; and pachymetry along the horizontal and vertical meridians were collected from the Pentacam® HR at baseline, after one night of lens wear, and at the latest visit. ResultsThe mean age of subjects was 12.03 ± 3.80 years at the time of OK lens fitting and wore OK overnight for a mean duration of 666 days (range 206–1736 days). The baseline spherical equivalent refractive error was −3.03 ± 1.56 D (range −1.00 to −6.00 D). The corneal volume increased significantly after OK wear (p = 0.001). Corneal densitometry increased after OK wear, but the change did not reach statistical significance (p = 0.113). Pachymetry in the central cornea did not change significantly across all visits (p > 0.05) but increased significantly in the mid-peripheral regions of the cornea. Baseline refractive error was not found to be correlated with the changes in corneal volume, corneal densitometry, or pachymetry. ConclusionThe increase in corneal volume and densitometry and no significant change in the central corneal thickness may indicate the presence of corneal oedema from long-term OK wear. The baseline refraction was not correlated with the changes in corneal volume, densitometry or pachymetry.

The mid-term effect of corneal collagen cross-linking for progressive keratoconus and the changes in rigid gas permeable contact lens fitting parameters

Objective: To investigate the effect of corneal collagen cross-linking (CXL) for progressive keratoconus and to evaluate changes in the parameters of rigid gas permeable contact lens (RGPCL) fitting after surgery. Methods: It was a prospective cohort study. Fifty-three eyes of 41 keratoconus patients received accelerated CXL in Qingdao Eye Hospital of Shandong First Medical University from May to December 2018. There were 31 males and 10 females, aged (20.46±4.15) years. According to the corneal thickness, de-epithelial CXL (33 eyes) or trans-epithelial CXL (20 eyes) was performed. The best spectacle-corrected visual acuity, refractive power and the thinnest corneal thickness at baseline and at 6 weeks were compared. Corneal topography was performed at baseline and at 6 weeks, 3, 6 and 12 months postoperatively. Rose K RGPCLs were used before and 6 weeks after surgery, and the fitting status was monitored until 12 months after surgery. The t test was performed to analyze the difference before and after the operation. Results: The best spectacle-corrected visual acuity, refractive power, and the thinnest corneal thickness were not significantly changed over 6 weeks of follow-up, but the Kf, Ks and Kmax values were significantly increased in all patients (all P<0.05). In the de-epithelial group, the Kmax values before the operation, at 3, 6 and 12 months after the operation were (55.00±5.51) diopters (D), (54.73±5.34) D, (54.58±6.15) D and (54.20±5.49) D, respectively, and the decrease at 12 months was significant [(0.80±2.05) D; t=2.25, P=0.001]. In the trans-epithelial group, the Kmax values were (59.43±8.98) D, (57.97±8.79) D, (58.19±8.37) D and (56.94±7.19) D at the four time points, respectively, and the decreases at 3, 6 and 12 months were all significant [(1.46±2.09) D, (1.25±1.82) D, (2.49±3.64) D; t=3.12, 3.06, 3.50; P=0.006, 0.006, 0.007]. The best RGPCL-corrected visual acuity, the diameter and the average diopters of RGPCLs showed no significant change in both groups. The RGPCL base curve decreased by 0.07 mm in the de-epithelial group and by 0.13 mm in the trans-epithelial group (both P<0.05). The design of edge lifting was used in 10 eyes postoperatively in the de-epithelial group compared with 8 eyes preoperatively, and in 4 eyes postopratively in the trans-epithelial group compared with 7 eyes preoperatively. The number of eyes using the toric peripheral design of the lens was increased to 3 compared with 2 preoperatively in the de-epithelial group and from 1 to 4 in the trans-epithelial group. The acceptance rate of RGPCL fitting in both groups increased at 6 and 12 months after surgery compared to 6 weeks after surgery. Conclusions: The corneal curvature became steep slightly at 6 weeks after CXL and gradually recovered and flattened. The Kmax in the trans-epithelial group decreased earlier and more than that in the de-epithelial group. The base curve of the RGPCLs was slightly reduced after 6 weeks, and the toric peripheral design was increasingly needed, but the requirement for the design of the lifted edge was different between the two groups. A good RGPCL fitting can be achieved within 1 year after CXL.

How Can We Best Measure the Performance of Scleral Lenses? Current Insights

Scleral lenses (SLs) present several unique advantageous characteristics for patients. As these lenses are mainly fitted in severely diseased eyes, a thorough evaluation of the ocular surface before and after SL fitting and the on-eye SL fitting evaluation are essential and help minimize potential physiological complications. This review will explore the current and emerging techniques and instrumentation to best measure SL performance ensuring optimal lens fitting, visual quality, comfort and physiological responses, highlighting some potential complications and follow-up recommendations. A single physician could perform the great majority of evaluations. Still, the authors consider that the assessment of SL fitting should be a collaborative and multidisciplinary job, involving contact lens practitioners, ophthalmologists and the industry. This publication has reviewed the most up-to-date work and listed the most used techniques; however, the authors encourage the development of more evidence-based recommendations for SL clinical practice.

Contact lens prescribing trends in the UK hospital eye service

PurposeThe aim of this study was to evaluate the types of contact lenses fitted by hospital optometrists within the Midlands region of the United Kingdom (UK). MethodA questionnaire was sent to all the lead optometrists of the Midlands Hospital Optometry Group (MHOG). This group includes optometry hospital eye departments within the Midlands region of the UK. The questionnaire requested information of their last ten contact lens fitting appointments. Details of the patient’s age, gender, lens type, wearing times, and presenting condition were retrospectively taken from the patients’ records using the appointment diary to identify the last ten patients fitted with contact lenses. ResultsDetails from a total of 109 contact lens fits were collected. This included 45 females and 64 males with a mean age of 39.4 ± 17.4 years. The mean wearing time was 6.3 ± 1.0 days per week and 10.7 ± 5.1 h per day. Sixty-one percent of the contact lenses fitted were for patients with keratoconus and over half of all the contact lenses fitted were corneal rigid gas permeable lenses. ConclusionThis study highlighted that the main reason for fitting contact lenses in hospital contact lens practice is primary corneal ectasia, and mainly keratoconus. Whilst most patients with keratoconus were fitted with corneal rigid gas permeable contact lenses, around 1 in 6 were fitted with soft contact lenses. This study addresses a gap in the literature about contact lenses fitted in UK hospitals and how they differ from community contact lens practice.

Keratoconus management at public sector facilities in KwaZulu-Natal, South Africa: Practitioner perspectives

Background: Keratoconus (KC) is a non-inflammatory, self-limiting corneal ectasia that causes reduced visual acuity and if left undiagnosed and/or untreated may lead to visual impairment. Optometrists remain the first point of contact for affected patients, making appropriate timeous care essential.Aim: To investigate keratoconus management in the public sector in KwaZulu-Natal, South Africa.Setting: Public sector eye care facilities in KwaZulu-Natal, South Africa.Methods: In a quantitative, cross-sectional study, a questionnaire was distributed to optometrists employed by the Department of Health in KwaZulu-Natal (DoH-KZN). Data on practitioner demographic profile and clinical competence, facility attendance statistics, resources available and KC clinical protocols were collected.Results: The response rate was 36 (71%). The optometrists’ mean age was 30.19 ± 4.53 years, and 80% of them had work experience of less than 10 years. The majority of the health facilities (63.9%) reported a monthly attendance of 51–300 patients, and, of these, 72% of the respondents reported seeing only between 1 and 10 keratoconic patients. A lack of equipment and/or fitting of contact lenses being disallowed by the DoH-KZN were cited by the majority (61%) as the reason for routinely referring KC patients to optometrists in private practice.Conclusion: This study highlights a deficiency in the minimum standard of optometric care for KC in the public sector in KZN, primarily because of a lack of equipment and resources. It is recommended that the management of KC at all levels of the public health system be reviewed to improve the quality of service for keratoconic patients.

Aktueller Stand zur Topographie der Sklera – eine Literaturrecherche

Purpose. Although a major part of the anterior surface of the eyeball is formed by the sclera, there is little confirmed data on topography of the sclera compared to the cornea. The goal of this paper was to provide an update of relevant literature published on anatomy and topography of the anterior sclera. Methods. A systematic literature search was conducted in PubMed using the key words “scleral” and “topography.” 66 of the 310 papers dealt with the topic and were used for this present review. In addition, 5 articles from the Germanlanguage non-peer-reviewed literature were included. Results. Several studies have demonstrated the utility of modern measurement and examination techniques, such as optical coherence tomography (OCT), Scheimpflug imaging, or Fourier-based profilometry in the assessment of scleral parameters. These allow a more comprehensive understanding of the structure and shape of the anterior sclera, simplified contact lens selection, prediction of lens fit, and assessment of changes in scleral topography. The shape of the sclera can be influenced by factors such as age, refraction, accommodation, convergence, thickness, stiffness, modulus of elasticity, intraocular pressure, keratoconus and contact lens wear. Conclusion. A comprehensive understanding of the biometric properties and topography of the sclera of the anterior segment of the eye is an essential component for both the design and fitting of scleral as well as soft contact lenses. Keywords Sclera, topography, anatomy, Scheimpflug, profilometry, optical coherence tomography

Effects of Medium-Term Soft Contact Lens Fitting on Dry Eye: Analyses Using Ultra-High Resolution Optical Coherence Tomography and Digital Slit-Lamp Biomicroscopy.

Purpose This study aimed to evaluate the medium-term fit of soft contact lenses (SCLs) and its effects on dry eye by using ultra-high-resolution optical coherence tomography (UHR-OCT) and digital slit-lamp biomicroscopy (DSLB) and identify factors indicating a better contact lens fit. Methods A total of 14 participants (7 men, 7 women; mean age, 23.1 years) were recruited. Temporal lag and conjunctival coverage were imaged by UHR-OCT. DSLB was used to assess lens decentration and blink-induced movement. In addition, dry eye indices, including ocular surface disease index (OSDI), tear break-up time (TBUT), and Schirmer I test scores, were measured at baseline and 1 day, 1 week, 1 month, 3 months, and 6 months after wearing. Results Good repeatability was found in the assessments of lens fit characteristics by two researchers and in the assessments by one researcher at different follow-up times. There were no significant differences in lens fit characteristics, TBUT and Schirmer I test scores at each checkpoint (P >0.05). However, the OSDI was significantly higher than baseline after wearing (P <0.05). Changes in the temporal lag were positively correlated with changes in TBUT (r =0.544, P =0.044) and negatively correlated with changes in OSDI (r = -0.629, P =0.016). Changes in blink-induced movement were positively correlated with changes in OSDI, Schirmer I test scores, and TBUT (P <0.05). Conclusions UHR-OCT and DSLB can be used to comprehensively and quantitatively evaluate SCL fit. Both the contact lenses and ocular surface conditions are almost stable within 6 months of SCL wear. Temporal lag and blink-induced movement have a strong correlation with dry eye parameters in SCL wearers.

Orthokeratology and high myopia

The aim of this study is to review the current literature on ortho-K lenses use in myopia with a particular focus on the efficacy and safety of orthokeratology in myopia, and its effects in the case of high myopia, as well as the impact of COVID-19 pandemic on myopia and orthokeratology. COVID-19 pandemic influenced the incident of myopia as well as progression of myopia. Ortho-K lenses have been shown to be safe and effective in reducing the axial elongation and decreasing myopia progression in low to moderate myopia and with some limitations in high myopia patients. During the COVID-19 pandemic, ortho-K treatment was not affected, and the pandemic had no effect on the axial elongation in myopia children undergoing treatment with ortho-K lenses. Myopia is becoming a major health problem worldwide that is increasing to an alarming rate. The progression of myopia can lead to serious irreversible complications. There is sufficient evidence proving that orthokeratology lenses are effective and safe in myopia. More studies need to be done in high myopia. Long term success of the use of ortho-k lenses increases with the proper lens fitting.

Anterior Segment Optical Coherence Tomography In Scleral Lens Fitting

Background: AS-OCT is a noncontact imaging device that provides the detailed structure of the anterior part of the eyes. The Objectives In this review, the author will discuss the clinical applications of AS-OCT in the scleral contact lens fittings.Material &amp; Methods:Pre-Scleral lens fit and post fit ASOCT done on 30 patients to assess the normal fitting and compare it with the slit lamp evaluation.Results:ASOCT gives a Quantitative measurement of the fit.Conclusions:ASOCT comes out as a helpful tool for beginners particularly for a good assessment of a contact lens fit. The author also presents some interesting cases demonstrated via AS-OCT.