Measurement Of Retinal Sensitivity Research Articles

FUNCTIONAL–MORPHOLOGIC CORRELATES IN PATIENTS WITH BRANCH RETINAL VEIN OCCLUSION AND MACULAR EDEMA

To investigate the relations among best-corrected visual acuity, retinal sensitivity, retinal thickness, and retinal volume in patients with branch retinal vein occlusion, and macular edema. In 49 consecutive patients with branch retinal vein occlusion (mean age, 68.2 ± 9.9 years; 25 women and 24 men), macular function was documented by microperimetry and best-corrected visual acuity was determined on the logarithm of the minimum angle of resolution scale. Retinal thickness and retinal volume were measured by optical coherence tomography, and mean retinal sensitivity was calculated for each of nine macular subfields on the retinal map obtained by optical coherence tomography. Pearson correlation coefficients were calculated and multiple linear regression analysis was performed with 7 variables (age, gender, hypertension, hyperlipidemia, duration of branch retinal vein occlusion, nonperfused retinal area, and serous retinal detachment). On multivariate analysis, best-corrected visual acuity was significantly correlated with both retinal thickness and volume in 4 of 9 retinal subfields (fovea, superior inner, inferior outer, and nasal inner). In contrast, retinal sensitivity was correlated with both retinal thickness and volume in all 9 retinal subfields. Retinal thickness and retinal volume are more closely associated with retinal sensitivity than with best-corrected visual acuity. Measurement of retinal sensitivity may be useful for assessing branch retinal vein occlusion patients with macular edema.

Measurements of retinal sensitivity on a cellular scale

Measurements of retinal sensitivity on a cellular scale

Changes in visual function and thickness of macula after photodynamic therapy for age-related macular degeneration

To determine the correlation between the changes in the central retinal sensitivity and the changes in the foveal thickness (FT) after photodynamic therapy (PDT) for age-related macular degeneration (AMD). Nineteen eyes of 19 patients with choroidal neovasularizations (CNVs) secondary to AMD were studied. The pretreatment values of the central retinal sensitivity determined by Micro Perimeter 1 (MP1; Nidek Technologies), best-corrected visual acuity (BCVA), and optical coherence tomography (OCT)-determined FT were compared to the postoperative values at three and six months after PDT. At six months, the retinal sensitivity within the central 10 degrees was significantly improved (P = 0.02) and the FT was significantly thinner (P = 0.016). The BCVA, however, did not change significantly (P = 0.80). The changes in the retinal sensitivities were significantly correlated with the changes in the decrease in the FT (r = - 0.59, P = 0.012 within the central 10 degrees ) at six months after PDT. Significant improvements in retinal sensitivities within the central 10 degrees and a decrease in FT were observed even though the BCVA was not significantly improved. The measurement of retinal sensitivity by MP1 may be a better method to assess central visual function than the conventional visual acuity after PDT.

Relationship between retinal nerve fibre layer measurements and retinal sensitivity by scanning laser polarimetry with variable and enhanced corneal compensation

Aim:To evaluate the relationship between retinal sensitivity and the retinal nerve fibre layer (RNFL) measurements by scanning laser polarimetry (SLP) with variable corneal compensation (VCC) and enhanced corneal compensation (ECC)...

Effect of Laser Spot Diameter on the Reproducibility of Visual Field Analysis in Diabetic Patients with Upper Temporal Retinal Vein Occlusion

Aim: To evaluate the effect of the laser spot diameter on the reproducibility of the visual field analysis in diabetic patients with upper temporal retinal vein occlusion. Material and Methods: Thirty-six eyes of 36 consecutive type-2 diabetes mellitus patients with upper temporal retinal vein occlusion who required sectoral retinal photocoagulation (SRP) treatment were enrolled for the study. Patients with a history of previous retinal laser photocoagulation, significant lenticular opacities and those whose perimetric test reliability criteria were low (fixation loss >20% and false-positive or false-negative responses >33%) were excluded from the study. SRP was applied to the upper temporal retinal quadrant. Nineteen eyes received SRP treatment with 500-µm laser spots (group 1) while the rest of the eyes (n = 17) received SRP with 300-µm laser spots (group 2). Patients underwent five consecutive visual field analyses, each on a different day during a 2-week period, both before and 6 weeks after SRP. The Humphrey field analyzer central 30–2 threshold test using SITA Standard strategy was applied for visual field testing. Results: The mean age of the patients in groups 1 and 2 were 58.6 ± 6.7 and 59.1 ± 7.1 years, respectively (p > 0.05). Pre-SRP mean retinal sensitivities of the lower nasal quadrant in groups 1 and 2 were not different statistically (p > 0.05). Post-SRP mean retinal sensitivity of the lower nasal quadrant was significantly higher in group 2 than group 1. Moreover, mean defect has been found to be lower in group 2 (p < 0.05). The coefficient of variation for pre-SRP retinal sensitivity measurements were 7.9 and 7.6% for groups 1 and 2, respectively (p > 0.05). The coefficient of variation for post-SRP retinal sensitivity measurements were 3.8 and 2.1% for groups 1 and 2, respectively (p < 0.05). Conclusion: SRP treatment with 300-µm diameter laser spots may yield more reproducible visual field data than that with 500-µm diameter laser spots. Moreover, the improvement in the retinal sensitivity of the patients with branch retinal vein occlusion is more marked in case where 300-µm laser spots are used.

Preservation of visual responsiveness in the superior colliculus of RCS rats after retinal pigment epithelium cell transplantation

The dystrophic RCS rat undergoes progressive photoreceptor degeneration due to a primary defect in retinal pigment epithelial (RPE) cells. This has a major impact on central visual responsiveness. Here we have examined how functional deterioration is contained by subretinal transplantation of immortalized human RPE cells. Transplantation was done at three to four weeks of age prior to significant photoreceptor loss and recipients were kept on cyclosporin. At six months of age, sensitivity maps and multi-unit response properties were obtained across the visual field by recording at 76 equidistant sites encompassing the whole superior colliculus. A significant degree of functional protection, both in terms of area of responsive retina and response characteristics was observed following RPE transplantation. At best, the sensitivity, latency of onset, and response rise time were all maintained within normal ranges and this was achieved with no more than half of the normal complement of photoreceptors. Although partial, the degree of anatomical preservation (both in terms of outer nuclear layer thickness and area of rescue) correlated well with the level of preserved visual sensitivities. Sham injections also resulted in rescue, though the area of preservation was strictly confined to the needle injury site and the response properties were significantly worse than with RPE injections. This study shows that central physiological responsiveness and correlated retinal morphology can be preserved in an animal model of retinal disease by implantation of an immortalized cell line. The use of retinal sensitivity measurements provides a background for assessing higher visual functions in these animals and a direct comparison for human perimetry measures.

The luminous efficiency of light entering the eye pupil at different points and its relation to brightness threshold measurements

In previous papers (Crawford 1936) results have been given for the variation of pupil size and of brightness threshold (measured with small artificial pupil) with time after changing from a high to a low general light stimulus. These results cannot, however, be immediately combined to give the response of the eye as a whole (with natural pupil) until the possible effects of the efficiency of light entering the eye through different parts of the pupil have been investigated. It has been found (Stiles and Crawford 1933) that light entering the eye near the periphery of the pupil is less efficient in producing the sensation of brightness than light entering near the centre. Probably the same thing occurs for the threshold of the sensation of brightness, so that the threshold would be higher for light passing through the more peripheral parts of the pupil. The first part of this paper is concerned with the testing of this hypothesis. The results are expressed in the form of curves connecting brightness threshold with distance of the point of entry of the light from the centre of the pupil, these curves being called, for convenience, threshold efficiency curves. The measurements of this effect made hitherto have related to the foveal region of the retina and a fairly high field brightness. They are here extended, by the threshold brightness method, to regions of the retina more or less distant from the fovea and to field brightnesses extending down to zero. In order to complete the picture of the luminous efficiency effect, in so far as it relates to white light, it remains only to investigate the course of the variation in shape of the threshold efficiency curve with time after the field brightness is changed suddenly from one value to another. One case only has been dealt with, namely, the change from a high value of field brightness to zero. Finally, all these results may be combined with the corresponding measurements of pupil size and retinal sensitivity to give the response of the complete eye.