Medical hypothesis, discovery & innovation in optometry

Background: Parkinson's disease (PD) is the second most common neurodegenerative disorder. We aimed to review both the disease and the drug-related ocular manifestations of PD.
Methods: In this manuscript, we have reviewed and summarized existing literature on the ocular manifestations and drug-related complications of PD. We have also discussed the use of current noninvasive imaging techniques, such as optical coherence tomography (OCT), for the early diagnosis and monitoring of PD.
Results: Impaired color vision, reduced stereopsis, reduced contrast sensitivity, pupillary abnormalities, eye movement disorders, convergence insufficiency, dry eye syndrome, glaucoma, visual dysfunctions, retinal abnormalities, and drug-related side effects were among the listed ocular manifestations of PD. There is a large knowledge gap regarding the type of glaucoma affecting PD patients-whether it is open-angle or other types. Further case studies and long-term follow-ups during PD progression are necessary to fill this gap. Patient compliance with follow-up visits for more visual field tests and OCT during PD progression may become problematic when dementia and cognitive impairment occur.
Conclusions: There is a general need for clinicians to perform further tests and more visual examinations to rule out ocular manifestations. Furthermore, additional clinical trials are needed to further evaluate the use of different types of OCT findings as biomarkers of PD progression. This would aid in early diagnosis and in delaying disease progression, if treated promptly.

Background: To determine the normative data and reference value for photostress recovery time (PSRT) following exposure of the macula to light, in various age groups within the Indian population.
Methods: Cross-sectional observational study performed from November 2015 to July 2016 in the Bangalore district of Karnataka state in India. We examined a total of 1,282 eyes of 641 participants and included those with corrected distance visual acuity (CDVA) scoes lower than  or equal to 0.4 Logarithm of the Minimum Angle of Resolution (LogMAR). We performed the photostress procedure under standard conditions using the same approach.
Results: The mean ± standard deviation (SD) of the age of participants age was 32.04 ± 15.80, with an age range of 8 to 70 years. The PSRT in participants below 16 years and above 45 years of age were significantly different compared to the 16-25-year-old age group (P  <  0.0001 for both). The PSRT values were significantly different between males and females in the reproductive age group (16 to 45 years old) (P  < 0.0001), but not in the other age groups.
Conclusions: The PSRT values were significantly different in children and older patients compared to the 16 to 25 years age group. We found that as age increased, PSRT increased significantly.

Background: The purpose of this study was to analyze optical coherence tomography (OCT) parameters of the choroid and retina in subjects with pre-manifest and manifest Huntington's disease (HD).
Methods: In this case-control study, the retinal parameters of patients with genetically confirmed HD and healthy controls were evaluated using spectral-domain optical coherence tomography (SD-OCT). Genetic and neurological assessments were performed besides a thorough ophthalmological examination. Contrast Sensitivity (CS) logarithm was evaluated using the Freiburg Vision Test. The association between OCT parameters and clinical and genetic characteristics was studied.
Results: A total of 91 subjects, including 60 HD subjects (60 eyes) and 31 control subjects (31 eyes) were eligible according to the inclusion and exclusion criteria. The range of the CAG (cytosine-adenine-guanine) repeat expansion size was 38-56 repeats, the mean ± standard deviation (SD) of the Unified HD Rating Scale (UHDRS) motor scores was 36.3 ±29.7, and disease duration was 13.7 ±7.2 years in HD subjects. Compared to the control group, significant decreases in the mean ganglion cell complex thickness and mean, temporal, superior, inferior, and nasal retinal nerve fiber layer (RNFL) thickness in HD subjects was revealed in OCT examination (P-values < 0.001, < 0.001, < 0.001, 0.023, 0.007 and 0.014, respectively). An inverse correlation between the disease duration and the mean RNFL thickness (r =- 0.470, P = 0.002) was found.
Conclusions: Localization of retinal thickness loss shows a specific pattern of retinal neurodegeneration in HD, similar to Parkinson disease and mitochondrial diseases. The association with the disease duration confirms the progressive nature of these changes.

Background: This study was performed to evaluate the use of anterior segment images, obtained with an automatic refractometer, to identify early defects of the iris pigment epithelium in patients with pigment dispersion syndrome (PDS) or pigmentary glaucoma (PG) without observable alterations at the slit lamp.
Methods: In this cross-sectional observational study, carried out from January 2018 to December 2019, in Policlinico Citta di Udine Health Center, Udine, Italy, we observed anterior segment infrared images of 1700 subjects who were undergoing routine ophthalmological examination using an automatic refractometer. We selected infrared images of subjects who fulfilled the inclusion and exclusion criteria and looked for a focal defect in the iris pigment epithelium.
Results: Twenty patients with focal iris pigment epithelial defect were identified and none of them showed evident signs of PDS. After the necessary explanations, they agreed to have further examinations to verify the possibility of PDS. An in-depth evaluation of ocular structures, including gonioscopy, demonstrated the presence of PDS in all subjects with iris defects.
Conclusions: The use of infrared images obtained by an automatic refractometer could provide early and easy identification of PDS in crowded ophthalmology clinics or mass screening programs; yet, more well-designed studies are necessary to confirm these preliminary findings and prove this proposed screening tool.

Background: The microbiome is strongly linked to many extra-intestinal disorders. Gut commensal microbiota, in particular, plays an active role in human immune and intestinal homeostasis. Complex interactions of the microbiota with host genetics and other underlying factors lead to intestinal dysbiosis, which is thought to be linked to ocular inflammatory diseases. Thus, the aim of this review is to analyze the role of intestinal microbiome in age-related macular degeneration (AMD).
Methods: A thorough literature search was performed using PubMed/MEDLINE, limited to English language publications, from January 2004 to March 2020. An additional search was made employing Google Scholar to complete the collected data as per the above-mentioned time-line and language limitations. The main keywords used included age-related macular degeneration, microbiome, dysbiosis, autoimmunity, gut microbiota, epigenetics, immune-mediated inflammatory diseases, and gut-retina axis.
Results: Recent studies have proposed the role of intestinal microbiota in the pathogenesis of AMD. Changes in the microbiome have been shown to trigger several ocular inflammatory processes. There is increasing evidence demonstrating that intestinal microbial imbalance may play an important role in the pathogenesis of AMD.
Conclusions: This review summarizes how alterations in the intestinal microbiota can be associated with the pathogenesis of AMD and how new therapeutic modalities can be designed to target this microbiome to limit the severe nature of this disease. Future advances in microbiome research may unveil a new era in understanding and managing AMD.

 
Background: Flap creation is the most critical step of laser in situ keratomileusis (LASIK). The introduction of the femtosecond laser with its uniform flaps, which enhance the accuracy of LASIK, has decreased the risk of flap-related complications like buttonholes and incomplete flaps. We recommended femtosecond laser-assisted LASIK (FS-LASIK) in the presence of superficial corneal opacities.
Case Presentation: We report a case of a 31-year-old female who reported to the Cornea clinic of the Sohag Center for LASIK and Corneal Surgeries, Sohag, Egypt, complaining of bilateral decreased vision due to refractive error. The uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) were 0.01 and 0.7 with a refractive correction of -3.50Ds/ -3.00Dc x 172° in the right eye and 0.01 and 0.6 with a refractive correction of -1.75 Ds/-6.00Dc x164° in the left eye, respectively. Slit-lamp examination of the anterior segment showed bilateral superior vascularized corneal scars and a linear superior conjunctival scar suggestive of old trachoma. Corneal tomographic imaging with a Scheimpflug based tomography device (Oculus Inc., Wetzlar, Germany) revealed a symmetrical bow tie with a very steep cornea without other ectatic changes. The patient underwent bilateral FS-LASIK with an excimer laser. No intraoperative complications occurred. She was followed up for two years with serial corneal topographies and stable post-LASIK results and visual outcomes.
Conclusions: FS-LASIK, in the presence of superficial corneal opacities, was safe and effective and induced no complications with special precautions. However, these findings are yet to be confirmed using well-designed clinical studies with larger samples and longer follow-ups.