ObjectiveTo study the oxygen saturation profile in normal Asian Indian eyes.DesignA cross sectional prospective study.SubjectsNinety eight consecutive patients presenting to our hospital with best corrected distance visual acuity (BCVA) of 20/20 and a normal ophthalmic examination were included in the study. Patients having any ocular or systemic disease were excluded from the study.Materials and MethodsOximetry was performed on all subjects with the Oxymap T1 retinal oximeter (Oxymap hf, Reykjavik, Iceland).Main Outcome MeasuresThe images were analysed for oxygen saturation and diameter.ResultsThe mean age was 33 years (Range: 18-63; SD: 12.4). The average arteriolar saturation was 90.3 ± 6.6% and the venous saturation was 56.9% ± 6.3. The average A-V (arterio-venous) difference was 33.2% ± 5.2. There was an increase in arteriolar (R2 = 0.264; p=0.001) and venous saturation (R2 = 0.151; p=0.001) with age. There was no significant change in the arterio-venous saturation difference (AVSD). The inferotemporal quadrant had the lowest saturations. Age correlated positively with ocular perfusion pressure (OPP)(R2 = 0.07; p=0.007). OPP correlated positively with global arteriolar saturation (R2=0.057, p=0.018).ConclusionThis study provides the normative database for an Indian population and is comparable to previous studies. Age, vessel diameter and OPP were the significant factors that influenced the saturation. Arteriolar and venous saturations increased with age while the AVSD did not change significantly.
Introduction:Diabetic macular edema (DME) is a vision-threatening complication of diabetic retinopathy. The current practice of management is a trial and error method of using intravitreal antivascular endothelial growth factor (VEGF)” or steroids to treat the patient and watch the response. However, if the patient's genetic profile helps us choose appropriate medicine, it would help customize treatment option for each patient. This forms the basis of our study.Materials and Methods:A case-control, prospective, observational series, where DME patients were treated with bevacizumab and subclassified as treatment naοve, treatment responders, and treatment nonresponders. Blood samples of 20 subjects were studied, with five patients in each of the groups (nondiabetic- group 1, treatment naοve- group 2, treatment responder- group 3, and treatment nonresponder-group 4). Whole blood RNA extraction followed by labeling, amplification and hybridization was done, and microarray data analyzed. Genes were classified based on functional category and pathways.Results:The total number of genes upregulated among all three experimental groups was 5, whereas 105 genes were downregulated. There were no common genes upregulated between the responders and nonresponders. There was only one gene upregulated between the diabetic and diabetic responders posttreatment. There were 19 genes upregulated and 8 genes downregulated in the inflammatory pathway in group 2 versus group 1. There were no downregulated genes detected in vascular angiogenesis and transcription group. There were identical numbers of genes up- and downregulated in the inflammatory pathway. Seventeen genes were upreguated and 11 genes downregulated in receptor activity, which remained the predominant group in the group classification.Discussion:In summary, this study would provide an insight into the probable signaling mechanisms for disease pathogenesis as well as progression. This type of study eventually would aid in developing or improvising existing treatment modules with a rational approach towards personalized medicine, in future addressing the differential responses to treatment.
Aim To describe the parafoveal cone arrangement in emmetropic subjects and its variations with eccentricity, meridians and change in axial length in Indian eyes. Methods We imaged 25 subjects using compact adaptive optics (AO) retinal camera prototype, the rtx1. Imaging was done at 1, 2, and 31 eccentricity from the fovea in four meridians: nasal, temporal, superior, and inferior. Results A statistically significant drop in the cone packing density was observed from 2 to 31 (21 eccentricity ¼ 25 350/mm 2 (5300/mm 2 , 8400-34 800/mm 2 ) 31 eccentricity ¼ 20 750/mm 2 (6000 mm 2 , 9000-33 670/mm 2 )) Po0.05. The spacing correspondingly increased with increase in distance from the fovea (21 eccentricity ¼ 6.9 mm (0.70 mm, 5.95-11.6 mm)) and 31eccentricity ¼ 7.80 mm (1.00 mm, 6.5-13.5 mm) Po0.05. As the axial length increases, the cone density significantly decreases. Interocular variations were noted. Conclusion With the advent of AO, visualization at the cellular level is now possible. Understanding the photoreceptor mosaic in the parafoveal space in terms of its density, spacing, and arrangement is crucial so as to detect early pathology and intervene appropriately. Newer therapeutic modalitites that are targeted at the cellular level like yellow micropulse laser, stem cells, gene therapy and so on may be better monitored in terms of safety and efficacy.
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