To compare the effect of the use of different lubrication eye drops and nonpreserved saline for the application of miniscleral contact lenses (CLs) on subjective experience during 6 hr of lens wear. Methods: Experienced soft CL wearers aged 18 to 45 years (inclusive) were enrolled in this prospective, randomized, double-masked, three arm comparison cross-over study. Subjects were custom fitted with KATT 16.5 mm diameter miniscleral lenses, ordered to their prescription. Subjects attended visits on three separate days and were randomized to receive instillation of an HP-guar/nanoemulsion drop or an HP-guar/sodium hyaluronate (HA) eye drop into the miniscleral lens before filling with saline or filling with saline alone (control). Subjective responses were collected up to 6 hr postapplication. Generalized linear mixed models with multinomial distribution and cumulative logit link were used to compare the rate at which responses improved post-CL application for the different treatments.Results: Twenty-four participants completed the study. Dryness symptoms were more likely to improve at a slower rate postlens application with saline alone compared with the addition of HP-guar/nanoemulsion (P¼0.005) or HP-guar/HA (P¼0.049) before lens application. Furthermore, the addition of HP-guar/nanoemulsion was more effective than saline alone in improving symptoms of fluctuating vision (P¼0.011), grittiness/burning/stinging (P¼0.001), and foreign body sensation (P¼0.006) more quickly. Conclusions: The use of postlens lubrication may be useful in enhancing adaptation to miniscleral lenses.
SIGNIFICANCE This research questions the validity of using the Sonogage ultrasound (US) pachometer to measure corneal epithelial thickness and coincidentally provides confirmation for the conventional view of the mechanism of orthokeratology (OK) based on central epithelial thinning. PURPOSE The Sonogage (Corneo-Gage Plus 1) pachometer uses A-scan US to measure total corneal thickness. It is claimed that this instrument can also measure corneal epithelial thickness. We sought to validate this claim by comparing total and epithelial thickness measurements with the Sonogage with those obtained with high-resolution optical coherence tomography (OCT). METHODS Fourteen non–contact lens wearers and 14 subjects who had worn Paragon CRT OK lenses overnight for greater than 1 month were recruited. Three OCT and five US measurements were taken in one eye of each subject. Depending on normality of data, paired t tests or Wilcoxon tests were used to compare total and epithelial thicknesses measured with the Sonogage pachometer and the Tomey Casia OCT. Pearson or Spearman correlation analyses were used to examine relationships between measurements obtained with the two instruments. RESULTS There was a significant difference in total corneal thickness measurements between the two instruments. Although a significant correlation was found (r = 0.916, P < .001), the Sonogage consistently measured greater total corneal thickness than did the OCT (+19.5 ± 9.2 μm; P < .001). Epithelial thickness using the Sonogage showed little variation (range, 46.4 to 50.0 μm), whereas epithelial thickness using the OCT ranged from 30.7 to 54.7 μm. There was no significant correlation between epithelial thicknesses obtained with the two instruments (r = −0.135, P = .49). Epithelial thickness measured by OCT was significantly thinner in OK wearers (35.8 ± 2.8 μm) than in nonlens wearers (46.7 ± 4.5 μm, P < .001). CONCLUSIONS The Sonogage is not able to measure epithelial thickness in vivo, returning essentially identical measurements over a range of epithelial thicknesses. Optical coherence tomography measurements confirm the conventional view of the mechanism of OK based on central epithelial thinning.
The specular microscopic findings in patients with xeroderma pigmentosum are suggestive of an accelerated endothelial cell loss. It is pertinent that the treating physicians must be involved in emphasising proper ocular protection from ultraviolet radiation to prevent avoidable blindness from xeroderma pigmentosum.
SIGNIFICANCE The front optic zone diameter of scleral contact lenses was manipulated to mimic the central treatment zone induced by orthokeratology contact lens wear, to explore potential effects on the peripheral refraction profile. PURPOSE The purpose of this study was to investigate effects on the peripheral refraction profile of changing front optic zone diameters of scleral contact lenses. METHODS Twelve young adults were fitted with scleral contact lenses (diameter, 16.5 mm) with two front optic zone diameters (6 and 4 mm) on one eye only on 2 separate days. Both lenses were fabricated with front optic zone power of −3.00 D and plano power outside the optic zone to mimic the orthokeratology treatment effect. All lenses had the same spherical back-surface design with a toric lens periphery. Peripheral refraction was measured at 10° increments along horizontal (±35°) and vertical (±30°) meridians before lens insertion and after 10 minutes of lens wear. Mixed-model analysis and post hoc t tests with Bonferroni correction were performed. RESULTS Compared with baseline, no significant change in relative spherical equivalent refraction M was observed with 6-mm optic zone lenses along the horizontal meridian. However, a significant difference in relative M profile was found with 4-mm optic zone lenses (P = .009). M became myopic at all locations in the nasal visual field (P < .05) except at 35°. In contrast, compared with baseline, no significant changes in relative M were found with either 6- or 4-mm optic zone lenses along the vertical meridian. CONCLUSIONS The greater myopic shift in relative peripheral refraction with 4-mm compared with 6-mm front optic zone lenses suggests that a reduced treatment zone diameter in orthokeratology may induce more myopic peripheral refraction changes. This may guide us toward novel orthokeratology lens designs for more effective myopia control.
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