Medical Hypothesis, Discovery & Innovation in Optometry

Background: Parkinson's disease (PD) is the second most common neurodegenerative disorder in the world. We aimed to review both disease and drug-related ocular manifestation of PD.

Methods: In this paper we reviewed and summarized papers concerning ocular manifestations of PD. This was a literature search on ocular manifestations and drug-related complications of PD. Also, use of current noninvasive imaging techniques such as optical coherence tomography (OCT) for the early diagnosis and monitoring PD were discussed.

Results: Impaired color vision, reduced stereopsis, reduced contrast sensitivity, pupillary abnormalities, eye movements disorders, convergence insufficiency, dry eye syndrome, glaucoma, several visual dysfunctions, retinal abnormalities, and drug-related side effects, were among the listed ocular manifestations of PD. There is a large gap regarding the type of glaucoma involved, 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. The problem could be patient compliance with the follow-up visits to do more visual field tests and OCT during PD progression, when dementia and cognitive impairment occur.  

Conclusions: There is a general need to perform further tests and more visual examinations to rule out these ocular manifestations by clinicians. Also, more clinical trials are needed to further evaluate different types of OCT as biomarkers in PD progression. This would aid in early diagnosis and delaying the progression of disease if treated promptly.

Background: To determine the normative data for photostress recovery time (PSRT) following light exposure of the macula, in various age groups within the Indian population.

Methods: This was a cross-sectional observational study performed during November 2015 and July 2016 in the Bangalore district of Karnataka state in India. We examined a total of 1282 eyes of 641 participants and included those with corrected distance visual acuity (CDVA) better or equal to 0.4 Logarithm of the Minimum Angle of Resolution (LogMAR). We performed the photostress procedure under the standard conditions using the same approach. Data was recorded and analyzed using parametric t-test. A two-sided p-value of <0.05 was statistically significant.

Results: The mean ± standard deviation (SD) of the participants’ age was 32.04 ± 15.80, with a 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-values < 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-value<0.0001), but not in the other age groups. 

Conclusions: The photostress recovery values were significantly different in children and older patients compared to 16 to 25 years old ones. We found that as age increased, photostress recovery time increased significantly.

Background: The purpose was to analyze analyze optical coherence tomography (OCT) parameters of choroid and retina in subjects with pre-manifest and manifest Huntington's disease (HD).

Methods: In this cross-sectional observational case-control study, the retinal parameters in HD and healthy controls were evaluated using optical coherence tomography (OCT). Statistical analysis was performed using SPSS 22.0 software package (Statistical Package for the Social Science for Windows, IBM Corp. Replicated 2013. IBM SPSS Statistics for Windows, version 22.0., Armonk, NY: IBM Corp).

Results: A total of 91 subjects, including 60 HD subjects (60 eyes) and 31 control subjects (31 eyes) were eligible based on 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. A significant decrease in the mean ganglion cell complex thickness, as well as mean, temporal, inferior, and nasal retinal nerve fiber layer (RNFL) thickness in HD subjects was revealed in OCT examination compared to the control group (P-values <0,001, <0,001, <0,001, 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’s disease and mitochondrial diseases. The association with the disease duration confirms the progressive nature of these changes.

Background: To evaluate the use of anterior segment images, obtained with an automatic refractometer, to identify early defects of the iris pigmented epithelium in patients with pigment dispersion syndrome or pigmentary glaucoma without observable alterations at slit lamp.

Methods: In this cross-sectional observational study, from January 2018 to December 2019, following verbal consent, we observed anterior segment infrared images of 1700 subjects looking routine ophthalmological examination using an automatic refractometer. We selected infrared images of subjects who fulfilled inclusion and exclusion criteria and looked for focal defect in the iris pigment epithelium. 

Results: Twenty patients with focal iris pigmented epithelial defect were identified, and none of them showed evident signs of pigment dispersion syndrome. An in-depth evaluation of ocular structures, including gonioscopy, demonstrated the presence of pigment dispersion syndrome in all patients with iris defects. In two patients with a previous diagnosis of pigmentary glaucoma, the infrared images were unremarkable, allowing a correct classification of the disease.

Conclusions: The use of infrared images obtained by an automatic refractometer could provide an early and easy identification of pigment dispersion syndrome in crowded ophthalmology clinics, yet, more -designed studies are necessary to confirm these preliminary findings.

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 the host genetics and other underlying factors create an intestinal dysbiosis which is thought to be linked to ocular inflammatory diseases.

Methods: A thorough literature search was performed in PubMed database. An additional search was made in Google Scholar to complete the collected items.

Results: Recent studies have proposed the role of intestinal microbiota in the pathogenesis of age-related macular degeneration (AMD). Changes in the microbiome have been shown to trigger several ocular inflammatory processes. There is increasing evidence that intestinal microbial imbalance may have 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 blinding nature of this disease. The future advances in microbiome may unveil a new era in understanding and managing AMD.

Background: Flap creation is the most critical step of laser in situ keratomileusis (LASIK). Also, the introduction of the femtosecond laser with its uniform flaps enhancing the accu­racy of LASIK has decreased the risk of flap related complications like buttonholes and incomplete flaps. We proposed femtosecond laser-assisted LASIK in the presence of superficial corneal opacities.

Case Presentation: We reported a case of a 24-year-old female patient presented to the Cornea clinic of the Sohag Center for LASIK and Corneal Surgeries, Sohag, Egypt, complaining of bilateral decreased vision due to bilateral refractive error. The uncorrected distance visual acuity (UDVA) in the right eye (OD) was 0.01 with corrected distance visual acuity (CDVA) to 0.7 in decimal by a refraction of -3.50Ds/ –3.00Dc x 172°, while the UDVA in the left eye (OS) was 0.01 with CDVA to 0.6 in decimal by a refraction of -1.75 Ds/-6.00Dc x164°. Slit-lamp examination of the anterior segment showed bilateral superior vascularized corneal scars. Corneal tomographic imaging by Scheimpflug based tomography device (Oculus Inc., Wetzlar, Germany) revealed a symmetrical bow tie with very steep cornea with no other ectatic changes. The patient underwent bilateral femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) using an excimer laser. No intraoperative complications occurred. She was followed up for two years with serial corneal topographies with 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.