Corneal Surface Elevation and Thickness in Relation to the Fit of Rigid Contact Lenses in Keratoconus and After Corneal Cross-Linking.

Purpose: To determine if factors pertaining to corneal thickness and elevation were linked to the prescribed back optic zone radius and overall diameter in keratoconus (group I), and cross-linked keratoconus (group II), cases successfully fitted with rigid contact lenses. Patients and Methods: A review of cases adapted to contact lens wear (Rose K™) and assessed using Pentacam™ (for corneal anterior surface topography, astigmatism, elevation, and topographic thickness variation) was undertaken to determine the significance of any correlation with comfort, lens usage, grading of keratoconus, corrected distance visual acuity (with glasses and contacts), refractive error, prescribed lens powers, back optic zone radius and overall diameter values were assessed. Results: Chief findings were, comfort was rated highly, lenses were worn for more than 10 hours/day in 75% of cases. RCL corrected distance logMAR acuities (median, mode, inter-quartile ranges) were 0.11, 0.12 (0.08-0.13) and 0.08, 0.08 (0.06-0.11) in groups I and II, respectively. Multiple linear regression revealed significant correlations (p<0.01) between the [A] back optic zone radius, the thinnest value of corneal thickness (x1) and anterior corneal surface elevation (x2). The respective r2 values were 0.471 in group I and 0.512 in group II. [B] overall diameter, x1 and x2. The respective r2 values were 0.282 in group I and 0.505 in group II. Conclusion: RCLs were well-tolerated in both groups. The r2 values imply there is a 50% chance of correctly predicting the suitable back optic zone radius in both groups, a 50% chance of correctly predicting the overall diameter in group II and 28% in group I cases using just x1 and x2. The thinnest value of corneal thickness and anterior corneal surface elevation could be used to quickly select the BOZR and OD during RCL fitting. This has the potential to reduce chair-time, waste and improve efficiency.

Prevalence of keratoconus in refractive surgery practice population in North Macedonia.

PURPOSE: To determine the prevalence of keratoconus (KC) in relation to ethnicity in a group of people who consulted an ophthalmological care institution seeking for refractive surgery in N. Macedonia. METHODS: This was a cross-sectional, interventional retrospective study. Chart reviews were performed for all new patients attending between January 2016 and January 2020 at the Sistina Ophthalmology Hospital in Skopje. All patients were screened; KC diagnosis and classification were based on the corneal topography. Ethnicity and gender classifications were according to patients' self-opinions. RESULTS: A total of 2812 patients charts reviewed. The mean age was 31.71 years (SD ± 9.73), and 1209 (43%) were male. A total of 2050 (72.9%) declared themselves as Macedonians, 649 (23.1%) Albanians, 76 (2.7%) Turks and 37 (1.3%) in other ethnicities. Differences in age between the ethnic groups were statistically significant (x2 = 90.225, p < 0.001). KC was diagnosed in 343 patients (12.2%), while 9 (0.7%) were KC suspects and 6(0.21%) presented pellucid marginal degeneration. KC was more frequent in males (n = 246, 71.7% of total) and skewed toward younger patients. Increasing patients' age decreased the odds of KC diagnosis by 3.7% (95% CI 1.8%-4.4%) per annum. Males were four times more likely to be diagnosed with KC (AOR = 4.01; 95% CI 3.12-5.16). In comparison with Macedonian patients, Turks were more likely to be diagnosed with KC (AOR = 4.09; 95% CI 2.47-6.78). There was no difference between Macedonians and Albanians (p = 0.08). CONCLUSION: The prevalence of KC at a refractive surgery practice in N. Macedonia is much higher compared with general population (6.8/100,000) and similar to the prevalence in Middle East Asia. Nationwide screening programs are needed to diagnose the disease earlier.

Are changes in visual acuity and astigmatism after corneal cross-linking (CXL) in keratoconus predictable?

PURPOSE: To evaluate changes in corrected distance visual acuity (CDVA), ratio of anterior and posterior corneal radii over the thinnest region of the cornea (ARC/PRC), and astigmatism after cross-linking (CXL) in keratoconus. METHODS: Subjective refraction and ARC/PRC (using Pentacam™) were monitored over 1 year in (I) keratoconus treated with routine CXL (n = 53), (II) relatively stable keratoconus (n = 23), and (III) age/gender matched controls (n = 24). RESULTS: CDVA (median, mode, interquartile range) improved significantly in group I, compared with groups II and III (p < 0.05), from 0.45 (0.60, 0.20-0.63) to 0.80 (0.95, 0.60-0.95); change in CDVA was associated with preop CDVA (p < 0.01 at all times postop). ARC/PRC (mean ± sd, 95% CI) changed from 1.362 (± 0.048, 1.347-1.377) to 1.425 (± 0.073, 1.401-1.449). CDVA and ARC/PRC remained stable in II and III. Significant relationships were revealed between logCDVA and ARC/PRC in I and II (at 12 months, I rs = - 0.464, II rs - 0.449) and logCDVA at postop(y), log CDVA at preop(x1), and ARC/PRC at preop(x2) in I (at 12 months, y = 0.356x1 - 1.312x2 + 1.806, r21 = 0.494, r22 = 0.203). Astigmatic power (mean ± sd, 95% CI) improved from - 3.10DC (± 1.52, - 3.55 to - 2.66) to - 2.53DC (± 1.24, - 2.90 to - 2.17) in I, and worsened from - 1.27DC (± 1.32, - 1.81 to - 0.73) to - 1.61DC (± 1.28, - 2.13 to - 1.09) in II. Vector analysis revealed in group I (a) the power of the surgically induced astigmatism (SIA) was linked to astigmatic power at preop and (b) the difference between the axis of astigmatism at preop(ø) and the axis of the SIA was linked to ø. CONCLUSION: CXL improved CDVA, increased the ARC/PRC ratio, and modified the association between CDVA and ARC/PRC. The change in CDVA was linked to preop CDVA and ARC/PRC values. The association between SIA and preop astigmatism implies there is not a simple cause and effect relationship with CXL.

First Experiences with Implantation of Phakic Lenses in Correction of Myopia in R. N. Macedonia.

Objective: Analysis of visual acuity parameters in patients with moderate to high myopia and myopic astigmatism 1 year after treatment with phakic intraocular lenses. Material and methods: This was a retrospective study on 35 patients (52 eyes) with moderate to high myopia who were implanted with the Visian V4c phakic implantable Collamer lens (Staar Surgical, Nidau, Switzerland). Examined parameters were: uncorrected distance visual acuity (UDVA) and best corrected visual acuity (CDVA), manifest and cycloplegic refraction, intraocular pressure, and endothelial cell count. The investigated parameters were measured preoperatively, 1, 3, 6 and 12 months postoperatively. Results: In 17 patients, phakic lenses were implanted binocularly and in 18 patients monocularly. Preoperatively 34.62% of patients had CDVA from 0.9 to 1.0. One year after the surgery 48.08% of patients had UDVA from 0.9 to 1.0. Preoperatively 80.77% of patients had diopter range from -6.00 Dsph to -10.00 Dsph. At 1 year postoperatively 78.85% of patients were within 0.00 Dsph to -1.00 Dsph. Preoperatively, in patients with astigmatism -4 Dcyl to -2 Dcyl dominated, as opposed to significant improvement postoperatively when 94.23% had astigmatism ranging from -1.0 Dcyl to 0 Dcyl. Conclusion: The implantation of phakic lenses demonstrated a successful postoperative outcome in the treatment of myopia and myopic astigmatism. Visual acuity and refraction show a gradual and significant improvement in visual function parameters within 1 year of lens implantation.

Keratoconus Progression Classification One Year After Performed Crosslinking Method Based on ABCD Keratoconus Grading System.

INTRODUCTION: Keratoconus is described as a degenerative bilateral, progressive, noninflammatory corneal disorder characterized by ectasia, thinning, and increased curvature. Keratoconus progression classification 1 year after performed crosslinking method in this study is based on the ABCD keratoconus grading system. AIM: To evaluate the possible keratoconus progression one year after performed a crosslinking (CXL) method based on the ABCD keratoconus grading system. Methods: Seventeen keratoconus patients (22 eyes) were included in this prospective study. CXL procedure was performed using the standard Dresden protocol at Eye Clinic Svjetlost Sarajevo with the inclusion period from January 2017 to January 2018. Twelve patients had monocular, and 5 patients had binocular treatments with follow up of 12 months. Preoperative and postoperative stages were compared using the ABCD keratoconus grading system measured on rotating Scheimpflug corneal tomography-based machine - Pentacam (Pentacam HR, Oculus Optikgeräte GmbH, Wetzlar, Germany). RESULTS: Out of 22 eyes, one eye had keratoconus stage I-II, 6 eyes had stage II, 4 eyes had stage III, and 9 eyes had stage III-IV. There was no statistically significant gradient change of keratoconus in comparison to one month after the surgery, p>0.05. There was no progression of the gradient when comparing to the preoperative stage. CONCLUSIONS: Corneal cross-linking could effectively stabilize the progression of keratoconus, as assessed by key corneal topographic parameters. Analyzing the trend of stage change in 12 months follow up after the crosslinking procedure of keratoconus patients there was no progression of a gradient in comparison to the preoperative stage. According to our results, we can conclude that CXL is a safe and effective procedure in treating keratoconus.

Cross-linking treatment for better visual acuity.

Aim To correlate the maximum anterior sagittal curvature (Kmax) changes and uncorrected (UDVA) and corrected distance visual acuity (CDVA) in keratoconus patients after the cross-linking (CXL) procedure. Methods Forty-four eyes of 34 patients with keratoconus were analysed after the standard Dresden protocol CXL procedure had been performed. All patients underwent complete preoperative examination with a follow-up of 12 months with focus on UDVA, CDVA and Oculus Pentacam (Scheimpflug technology) analysis. We analysed and correlated Kmax changes in the postoperative period of 12 months together with visual acuity changes. Results Visual acuity improved significantly in the first 3 months after the procedure and even more significantly until the end of the first year. Even Kmax is the most relevant and most followed parameter for progression and regression of keratoconus, its lowering was not directly correlated with the visual acuity improvement (both uncorrected and corrected) in the first 6 months after corneal CXL procedure. Kmax was changed significantly in the period of 12 months post cross linking, but not in the first 6 months. Conclusion Corneal CXL should be considered as a procedure not just for corneal stiffening and stabilization, but also for visual acuity improvement in keratoconus patients.