Clinical Performance of a New Bitangential Mini-scleral Lens.

SIGNIFICANCE: New bitangential mini-scleral lens designs provide a highly precise fit, follow the scleral shape, are comfortable to wear, and can correct residual astigmatism. This new scleral lens design complements the arsenal of medical contact lenses available to eye care practitioners. PURPOSE: The aim of this study was to evaluate the subjective and objective performance of a new mini-scleral lens design with a bitangential periphery. METHODS: In this observational study, data were collected for up to 15 months (median, 84 days; interquartile range, 76 days) from the left eyes of 133 patients fitted with this newly designed lens. Data were recorded during regular visits at Visser Contact Lens Practice's scleral lens clinics: diagnosis, clinical indication for scleral lenses, previous contact lens type, subjective performance, horizontal visible iris diameter, corrected distance visual acuity, and scleral lens fitting characteristics. RESULTS: The most common indication was keratoconus (45%), followed by irregular astigmatism (22%), keratoplasty (16.5%), ocular surface disease (13.5%), and other forms of irregular astigmatism (3%). The majority of patients (79%) scored comfort as either a 4 or 5 (out of 5), and 82% wore their lenses 12 hours or longer a day. Most lenses (81%) had a diameter of 16 mm (median, 16 mm; range, 15.5 to 17 mm) and were composed of Boston XO2 (46%), Menicon Z (44%), Boston XO (9%), or Boston Equalens II (1%). The median corrected distance visual acuity was 0.022 logarithm of the minimal angle of resolution (interquartile range, 0.155). The fitting characteristics revealed optimal values for centration and movement in 91% and 83%, respectively. Finally, the median stabilization axis was 50 degrees. CONCLUSIONS: New mini-scleral lenses with bitangential peripheral geometry yield satisfactory clinical results and good subjective performance and are therefore an effective option for managing patients who have irregular astigmatism or other corneal pathology.

Medical applications and outcomes of bitangential scleral lenses.

PURPOSE: To evaluate the clinical results of a new scleral lens design with a bitangential (nonrotationally symmetrical) periphery. METHODS: All the necessary data were obtained during the 1-year study period. The bitangential scleral lenses were fitted and monitored according to a standardized fitting methodology. They were cut by precise submicron lathing from high-oxygen-permeable materials (including 10 scleral lenses from Menicon Z material). Subjective performance, visual acuity, and scleral lens-fitting characteristics were recorded after a median of 9.4 weeks (range, 3 weeks to 1 year). RESULTS: Diagnoses in the 213 eyes (in 144 patients) were keratoconus (n = 121 eyes; 56.8%), ocular surface diseases (n = 31 eyes; 14.6%), penetrating keratoplasty (n = 29 eyes; 13.6%), and other forms of irregular astigmatism (n = 28 eyes; 13.1%). Many patients (164 lenses; 77.0%) gave high ratings for comfort. The most common diameter was 20.0 mm (162 lenses; 76.1%) (range, 18.5 to 21.5 mm). Median decimal best-corrected visual acuity with the bitangential scleral lenses was 0.8 (equivalent to Snellen 20/25) (range, 0 to 1.5). Most bitangential scleral lenses showed good fitting characteristics: optimal values were seen for lens movement (208 lenses; 97.7%) and lens position (208 lenses; 97.7%). Median central corneal clearance was 0.2 mm; clearances differed in the four peripheral directions. The median stabilization axis was 140 degrees (range, 0 to 180 degrees) in the right eyes and 60 degrees (range, 0 to 180 degrees) in the left eyes. CONCLUSIONS: The bitangential scleral lens-fitting and performance characteristics were clear and effective for the health professional and the patient. The high-oxygen-permeable material Menicon Z may, in theory, be of benefit to corneas with a high oxygen demand.