Does Adjunctive Under-flap CXL Reduce Regression for Hyperopic LASIK?

PURPOSE: To investigate whether adding accelerated under-flap corneal cross-linking to hyperopic laser in situ keratomileusis (LASIK-ufCXL) affects postoperative stability and regression, visual and refractive outcomes, and subjective quality of vision. METHODS: This prospective comparative contralateral eye study included 51 patients with hyperopia (102 eyes) who received LASIK-ufCXL in the eye with highest defocus equivalent (DEQ) or randomized when DEQ equal, with the contralateral control eye receiving LASIK alone. After excimer ablation, 0.25% riboflavin was instilled on the stromal bed for 3 minutes. The flap was repositioned, followed by a total irradiation dose of 3.24 J ultraviolet A (UV-A) light administered to the corneal surface, using 18 mW/cm2 UV-A for 3 minutes. Postoperative hyperopic regression (stability) was the primary outcome measure, defined by the difference in spherical equivalent (SEQ) at 1 week and 24 months postoperatively. Secondary measures reported uncorrected distance visual acuity, corrected distance visual acuity, cylinder vector analysis, subjective quality of vision, subjective night vision disturbances, and corneal haze. RESULTS: At 24 months, the SEQ stability (P = .4273) and the magnitude of hyperopic regression (P = .5613) did not significantly differ between groups, with a small trend showing hyper-opic regression of 0.50 diopters or greater being less frequent in LASIK-ufCXL eyes. There were no significant differences in accuracy, efficacy, and safety (P > .05), with a small trend of more residual refractive astigmatism in the LASIK-ufCXL group (P = .3216, Cohen's d: -0.29). Subjective quality of vision trended inferior in LASIK-ufCXL eyes (P = .2237, Cohen's d: -0.25), with a greater haze grading (P = .0466, Cohen's d: 0.41). CONCLUSIONS: Postoperative regression and stability were statistically equivalent between hyperopic LASIK vs LASIK-ufCXL, with identical safety. There were small clinical trends of lower efficacy, accuracy, and subjective quality of vision in LASIK-ufCXL eyes. [J Refract Surg. 2022;38(12):770-779.].

Short wavelengths filtering properties of sunglasses on the Canadian market: are we protected?

BACKGROUND: Exposure to solar radiation is a risk factor for multiple ocular pathologies. Ultraviolet (UV) radiation is involved in ocular diseases, including pterygium, ocular surface squamous neoplasia, and cataracts. High-energy visible light (HEV) is associated with age-related macular degeneration. Ocular protection against solar radiation seems essential to protect our eyes against the adverse effects of those harmful rays. Australia, New Zealand, Europe, and the United States are the only regions with mandatory standards for UV transmission for sunglasses. Adherence to Canadian standards by sunglasses manufacturers is not mandatory. In this study, we evaluated the UV and visible transmission of sunglasses in the Canadian market to test their compliance with Canadian standards. METHODS: The transmittance of 207 pairs of sunglasses, divided in 3 categories according to their price range, was measured. RESULTS: We show that close to 100% of the sunglasses tested respect the Canadian standards. The average HEV transmittance is around 10%, regardless the price range. CONCLUSIONS: Our study demonstrated that even if following Canadian standards is optional, most sunglasses sold on the Canadian market follow national and international standards. We also found that sunglasses filter around 90% of HEV. With the recent findings on the potential effects of HEV in retinal pathologies, we can ask whether this filtering capacity is sufficient to protect eyes from harmful HEV light. More work needs to be done to determine acceptable HEV light transmission limits to the existing Canadian standards.

Assessing the Contribution of the Oscillatory Potentials to the Genesis of the Photopic ERG with the Discrete Wavelet Transform.

The electroretinogram (ERG) is composed of slow (i.e., a-, b-waves) and fast (i.e., oscillatory potentials: OPs) components. OPs have been shown to be preferably affected in some diseases (such as diabetic retinopathy), while the a- and b-waves remain relatively intact. The purpose of this study was to determine the contribution of OPs to the building of the ERG and to examine whether a signal mostly composed of OPs could also exist. DWT analyses were performed on photopic ERGs (flash intensities: -2.23 to 2.64 log cd·s·m-2 in 21 steps) obtained from normal subjects (n = 40) and patients (n = 21) affected with a retinopathy. In controls, the %OP value (i.e., OPs energy/ERG energy) is stimulus- and amplitude-independent (range: 56.6-61.6%; CV = 6.3%). In contrast, the %OPs measured from the ERGs of our patients varied significantly more (range: 35.4%-89.2%; p < 0.05) depending on the pathology, some presenting with ERGs that are almost solely composed of OPs. In conclusion, patients may present with a wide range of %OP values. Findings herein also support the hypothesis that, in certain conditions, the photopic ERG can be mostly composed of high-frequency components.