Objective and subjective evaluation of the performance of medical contact lenses fitted using a contact lens selection algorithm

Bowman Layer Transplantation for Treating Keratoconus-Preliminary Findings

(1) Background: Mid-stromal isolated Bowman layer transplantation aims to reduce and stabilize corneal ectasia in patients with advanced, progressive keratoconus. The purpose of this review is to evaluate the effectiveness and safety of this new surgical technique. (2) Methods: Following the PRISMA statement and checklist, we searched Medline, the Cochrane Controlled Trials Register, and Embase and used a broad systematic search strategy according to the Cochrane Collaboration. (3) Results: Eight studies with a total number of 120 eyes of 106 patients met our inclusion criteria. One month after Bowman layer transplantation, patients with keratoconus showed a significant decrease in the measured simulated keratometry (-4.74 D [95% CI -6.79 to -2.69]) and the maximum keratometry (-7.41 D [95% CI -9.64 to -5.19]), which remained significant one year postoperatively (-2.91 D [95% CI -5.29 to -0.53] and -5.80 D [-8.49 to -3.12]). Intra- and postoperative complications were observed in 3% and 9% of the patients, respectively. An estimated success rate of 75% to 85% was achieved by experienced surgeons at 5 to 8 years postoperatively. (4) Conclusions: Bowman layer transplantation may be an effective and safe treatment option in patients with advanced, progressive keratoconus. Additional multicenter prospective interventional studies are needed to confirm these preliminary findings.

Irregular Astigmatism Management Using SPOT Scleral Lenses in the Treatment of Corneal Ectasia and Penetrating Keratoplasty

PURPOSE

To evaluate the outcome of SPOT scleral lenses in the management of irregular astigmatism in patients with corneal ectasia and penetrating keratoplasty. Second, we analyzed patients' characteristics and tolerance, comfort, and geometries of fitted lenses.

METHOD

Over a 5-year period, we included patients experiencing irregular astigmatism fitted with SPOT scleral contact lenses, from the University Hospital of Clermont-Ferrand, France. Data collected included corneal diseases, refractive error, best-corrected visual acuity (VA) with SPOT lenses, geometry of the lens, number of adjustment consultations, and the duration of follow-up. Comfort, quality of vision, less handling, and satisfaction were evaluated using visual analog scales after a 6-month follow-up period.

RESULTS

Sixty-five patients were included, analyzing 107 eyes. Eighty percent of patients still daily wore lenses after a follow-up of 22.3±13.8 months. Visual acuity improved by 0.47±0.51 logarithm of the minimum angle of resolution (average increase of 5 lines) (P<0.001) after wearing scleral lenses. Comfort, quality of vision, less handling, and satisfaction of contact lenses were excellent (>75/100). Contact lenses were daily worn 10.0±4.1 hr/day. Most patients wore size M (17 mm) lenses (53.3% of patients), with an average sagittal height of 5.2±1.2 mm. Internal toricity was used in 30% of cases. Best geometry was found after 2.69±0.87 consultations.

CONCLUSION

SPOT scleral contact lenses are an effective and well tolerated method to improve the VA of patients with irregular astigmatism.

Revisiting the Robustness of Pentacam HR Indices Against Soft Contact Lens Wear

Purpose

To evaluate various selected Pentacam HR indices in a cohort of soft contact lens (SCL) wearers before and after SCL discontinuation.

Methods

Ninety right eyes of 90 SCL wearers (group 1) were compared to healthy controls (group 2). For group 1 eyes, Pentacam HR images were captured within one hour of SCL removal and after one month of discontinuation. The evaluated indices included curvature, elevation, and pachymetric parameters.

Results

Elevation indices and two pachymetric indices (central corneal thickness and thinnest corneal thickness) did not show significant differences, either between the two groups or in group 1 after SCL discontinuation. Some pachymetric indices (average and maximum corneal pachymetry progression indices, and maximum Ambrosio's relational thickness index) showed statistically significant (P-value <0.001), yet clinically irrelevant differences. Contrarily, changes in curvature indices were both statistically significant (P-value <0.001) and clinically relevant.

Conclusion

From a clinical point of view, many elevation and pachymetric indices are robust against SCL wear, and can be relied upon for corneal ectasia screening of SCL wearers, even without abstaining from wearing SCLs.

Scleral lens wear following penetrating keratoplasty: changes in corneal curvature and optics

PURPOSE

Visual rehabilitation following penetrating keratoplasty is the primary indication for approximately 15% of all scleral lens fittings. Since corneal biomechanics are altered following penetrating keratoplasty, the aim of this study was to quantify changes in anterior corneal optics following short-term scleral lens wear in eyes with corneal grafts.

METHODS

Scheimpflug images were obtained before and after a period of scleral lens wear (mean 6.3 ± 1.4 h), from eyes that had previously undergone penetrating keratoplasty (10 eyes of nine participants, mean age 31 ± 9 years). Corneal power and thickness data were examined over the central 6 mm, including regional analyses of the central (0-3 mm) and the mid-peripheral cornea (3-6 mm annulus) using customised software to deterime corneal power vectors M (best fit sphere), J₀ (90/180 astigmatism) and J₄₅ (45/135 astigmatism). Anterior corneal aberrations were extracted using corneal elevation data.

RESULTS

Corneal power vector J₄₅ increased following lens wear (by 0.22 ± 0.05 D, p = 0.003) across the central 6 mm, while M displayed regional variations following lens wear indicating larger changes further from the corneal centre (p = 0.004). The change in corneal power vector M was also correlated with the magnitude of central corneal swelling (r = 0.65, p = 0.04). The anterior corneal aberration terms of oblique astigmatism, hoirzontal coma, and spherical aberration also varied following lens wear (all p ≤ 0.01). The mean change in the corneal spherocylinder derived from the elevation data following lens wear was +0.14/-0.54 × 44 for a 6 mm corneal diameter.

CONCLUSIONS

Clinically significant alterations in anterior corneal topography and higher order aberrations were observed following short-term scleral lens wear in eyes that had undergone penetrating keratoplasty. Spherocylindrical changes were approximately double the magnitude and more oblique in orientation compared to previous reports of healthy eyes. Changes in corneal power vector M may be related to epithelial corneal oedema.

Pathogenesis of Keratoconus: The intriguing therapeutic potential of Prolactin-inducible protein

Keratoconus (KC) is the most common ectatic corneal disease, with clinical findings that include discomfort, visual disturbance and possible blindness if left untreated. KC affects approximately 1:400 to 1:2000 people worldwide, including both males and females. The aetiology and onset of KC remains a puzzle and as a result, the ability to treat or reverse the disease is hampered. Sex hormones are known to play a role in the maintenance of the structure and integrity of the human cornea. Hormone levels have been reported to alter corneal thickness, curvature, and sensitivity during different times of menstrual cycle. Surprisingly, the role of sex hormones in corneal diseases and KC has been largely neglected. Prolactin-induced protein, known to be regulated by sex hormones, is a new KC biomarker that has been recently proposed. Studies herein discuss the role of sex hormones as a control mechanism for KC onset and progression and evidence supporting the view that prolactin-induced protein is an important hormonally regulated biomarker in KC is discussed.