Measurement of in vivo lens shapes using IOLMaster 700 B-scan images: Comparison with phakometry.

PURPOSE: This study compared in vivo crystalline lens shape measurements using B-scan images from the IOLMaster 700 with phakometry. METHODS: Twenty-four young adult participants underwent IOLMaster 700 and phakometry measurements under cycloplegia (1% cyclopentolate). The IOLMaster 700 generated B-scan images along six meridians in 30° increments, which were analysed using custom MATLAB software to determine lens surface radii of curvature. Phakometry measurements were obtained using Purkinje images reflected from the lens surfaces. RESULTS: The IOLMaster 700 image analysis method yielded a lower mean anterior lens surface spherical equivalent power (+6.20 D) than phakometry (+7.55 D); however, the two measurements were strongly correlated (R(21) = 0.97, p < 0.0001). The astigmatic power vectors (J0 and J45) for the anterior lens surface were significantly higher for the IOLMaster 700 measurements, with only J0 showing a significant moderate positive correlation (R(21) = 0.57, p = 0.005). For the posterior lens surface, the IOLMaster 700 measurements had a higher mean spherical power (+14.28 D) compared to phakometry (+13.70 D); however, a strong positive correlation (R(21) = 0.90, p < 0.0001) was observed. No significant correlations were noted for posterior lens surface astigmatic vectors (J0 and J45). The IOLMaster 700 estimates for the equivalent lens mean spherical power were slightly lower than those for phakometry, with a mean difference of -0.72 D, and both methods were positively correlated (R(21) = 0.94, p < 0.0001). CONCLUSIONS: The findings demonstrate that IOLMaster 700 B-scan image analysis technique provides similar estimates of lens surface powers to phakometry. These results highlight the potential of the IOLMaster 700 to provide measurements of lens shape, informing future research and clinical use.

Supplemental light exposure improves sleep architecture in people with type 2 diabetes.

AIMS: People with type 2 diabetes (T2D) suffer from sleep disorders, with the mechanism not clearly understood. In T2D, the light transducing retinal photoreceptors that regulate sleep behaviours are dysfunctional; hence, we determine here whether supplemental light exposure ameliorates sleep quality and daytime sleepiness in T2D. METHODS: Supplemental light (10,000 Lux, polychromatic) was self-administered for 30 min every morning for 14 days by ten participants with T2D with no diabetic retinopathy (DR). The effectiveness of supplemental light was assessed by comparing subjective sleep questionnaire (PSQI and ESS) scores and salivary dim light melatonin onset (DLMO) before and after the light exposure as well as with a self-maintained sleep diary during the light exposure. RESULTS: Compared to the baseline, supplemental light significantly improved the excessive daytime sleepiness score (p = 0.004) and phase-advanced the DLMO on average by ~ 23 min. Sleep diary analyses showed that afternoon nap duration significantly shortened over the first week of supplemental light exposure (p = 0.019). Afternoon naps and midnight awakening were significantly longer in diabetic participants with thinner perifoveal retina. CONCLUSIONS: In this case series, we provide initial evidence that supplemental bright light improves daytime sleepiness in T2D with no DR, with the critical period of light exposure showing a beneficial effect after one week. We infer that supplemental light augments photoreceptor signalling in T2D and therefore optimises circadian photoentrainment leading to improved sleep. Our findings inform the development of tailored light therapy protocols in future clinical trials for improving sleep architecture in diabetes.

Contact lenses for visual rehabilitation in Bilateral Nanophthalmos with Retinal Dystrophy- A case report.

BACKGROUND: Nanophthalmos is an uncommon developmental ocular disorder characterized by a small eye with short axial length, high hyperopia and high lens to eye volume ratio due to arrested development of the globe in all directions. Different types of fundus changes can rarely occur with nanophthalmos. OBSERVATIONS: This is a case report of a 17 years old female who presented with bilateral gradual progressive visual loss and photophobia at Tilganga Institute of Ophthalmology on 3rd July 2015. Her best corrected visual acuity was 20/300 with +12.00Ds/-1.00Dcyl@180 in the right eye and 20/200 with +12.00Ds/-1.50Dcyl@180 in the left eye. Axial lengths of two eyes were markedly shortened with pigmentary changes at the macula and dull foveal reflex along with retinal flecks in the mid-periphery. Full field ERG showed diminished rod and cone waves suggestive of rod and cone dysfunction. With the use of Rigid Gas Permeable (RGP) contact lenses, the acuity improved to 20/200 and 20/125 in the right and left eye respectively. CONCLUSION: This study proposes the use of contact lenses and light absorptive filters for better visual rehabilitation.