AIM:To determine the effects of change in light conditions on refractive error and visual functions including visual acuity,stereopsis and contrast sensitivity.METHODS:This cross-sectional study was conducted in the o...AIM:To determine the effects of change in light conditions on refractive error and visual functions including visual acuity,stereopsis and contrast sensitivity.METHODS:This cross-sectional study was conducted in the optometry clinic of the Shahid Beheshti School of Rehabilitation on 48 students in 2021-2022.All of them had eye health and normal visual function and could have refractive errors or not.Light intensity of 4 lx was considered equivalent to photopic light condition and light intensity of 1 lx was considered to be equivalent to mesopic light condition.The amount of refractive error was checked by auto refractometer and its changes in mesopic light condition were subjectively measured.Also,visual acuity,stereopsis and contrast sensitivity(in five spatial frequencies of 1.5,3,6,12,and 18 cycles per degree),were measured first in photopic light condition and then in mesopic light condition,by Snellen control vision chart,stereo butterfly test and the M&S technology monitor test respectively.RESULTS:In the 48 student subjects with an average age of 22.69±3.56y,mean of refractive error as sphere equivalent,visual acuity and stereopsis were-1.25±1.74 diopters,0 logMAR,44.37±13.03 seconds of arc,respectively in photopic light condition while in mesopic light was equal to-1.56±1.75 diopters,0.12±0.09 logMAR and 50.62±33.35 seconds of arc,respectively.The mean of contrast sensitivity measured at spatial frequencies of 1.5,3,6,12,and 18 cycles per degree in photopic condition was equal to 2.38±0.04,2.37±0.07,2.04±0.21,1.27±0.32,0.82±0.27 logarithm of contrast sensitivity,respectively and in mesopic lighting condition was equal to 2.34±0.12,2.30±0.16,1.84±0.28,1.02±0.28,0.63±0.24 logarithm of contrast sensitivity,respectively.Statistical analysis showed a significant difference between the two lighting conditions in all evaluated variables[refractive error(P<0.001),visual acuity(P<0.001),stereopsis(P=0.008)and contrast sensitivity(P<0.001)].CONCLUSION:The refractive error of the student subjects in mesopic light condition change towards myopia,and its amount is clinically significant.Also,the examination and comparison of the factors of visual acuity,stereopsis and contrast sensitivity in these two lighting conditions show that the decrease in brightness level to the mesopic level causes a decrease in the aforementioned visual functions.展开更多
AIM: To determine whether the photopic negative response(Ph NR) elicited by transient white flash on white background is characterizing for glaucoma model in rabbits.METHODS: Glaucoma was induced in twelve rabbits by ...AIM: To determine whether the photopic negative response(Ph NR) elicited by transient white flash on white background is characterizing for glaucoma model in rabbits.METHODS: Glaucoma was induced in twelve rabbits by subconjunctival injection of 0.05 m L of betamethasone in right eyes(each 1 m L contain betamethasone dipropionate5 mg and betamethasone sodium phosphate 2 mg).The intraocular pressure(IOP), electroretinogram(ERG) and visual evoked potential(VEP) were measured successively prior and on the 3, 7d, two weeks and four weeks postglaucoma induction. After four weeks, the animals were sacrificed and the globes were histopathologically examined.RESULTS: The IOP increased significantly after one week(P =0.0001), then it gradually returned to the control level. In ERG examination, the means of a and b wave amplitude and latency were not affected significantly.Ph NR amplitude decreased significantly within one week(P =0.0001), but its latency was not affected significantly(P =0.132). The means of VEP latency and amplitude were significantly affected after two weeks and four weeks of glaucoma induction(P =0.0001 and 0.02,respectively). The histopathologic examination of the globes showed reduced number of cells in the retinal ganglion cell layer with multiple vacuoles in the retinal nerve fibre layer.There was significant positive correlation between ganglion cell layer cells and Ph NR amplitude( r =0.8, P =0.002).CONCLUSION: The rise in IOP resulted in irreversible changes or incomplete recovery of VEP and Ph NR amplitude. Both Ph NR and VEP represented good additional tools in early diagnosis of glaucoma.展开更多
I am Dr. David P Pifiero from the Department of Optics, Pharmacology and Anatomy of the University of Alicante and from the Department of Ophthalmology of Vithas Medimar （Oftalmar） and Vithas Virgen del Carmen （Qv...I am Dr. David P Pifiero from the Department of Optics, Pharmacology and Anatomy of the University of Alicante and from the Department of Ophthalmology of Vithas Medimar （Oftalmar） and Vithas Virgen del Carmen （Qvision） hospitals in Spain.展开更多
Purpose:.To evaluate the diagnostic performance of the photopic negative response (PhNR) for the detection of primary open-angle glaucoma (POAG). Methods:.Fifty-two normal subjects (52 eyes) and 173 POAG patients.(173...Purpose:.To evaluate the diagnostic performance of the photopic negative response (PhNR) for the detection of primary open-angle glaucoma (POAG). Methods:.Fifty-two normal subjects (52 eyes) and 173 POAG patients.(173 eyes) were studied. The PhNR was elicited using a white stimuli on a white background..The mean deviation (MD) and pattern standard deviation (PSD) of the visual field were measured using standard automated perimetry (SAP)..Spectral domain optical coherence tomography (SD-OCT).was used to measure the mean thickness of the retinal nerve fiber layer (RNFL). Results:.In the glaucoma group,.as compared to the normal group,.the amplitudes of a-waves,.b-waves and PhNR were significantly smaller (P<0.001), and the PhNR implicit time was significantly longer.(P=0.004). The MD, PSD and mean thickness of the RNFL were significantly correlated with the amplitude of the PhNR (P<0.001). The area under the receiver operating characteristic curve (AUCs) for the amplitudes of a-waves,.b-waves and PhNR were 0.853,.0.830 and 0.918, respectively. When the specificity was ≥95%, the sensitivities were 60.4%, 54.2% and 85.4% respectively. Conclusion:The PhNR amplitude was reduced even when the loss in visual field sensitivity was mild, which suggests that PhNR might be a useful indicator of early glaucoma disease.展开更多
文摘AIM:To determine the effects of change in light conditions on refractive error and visual functions including visual acuity,stereopsis and contrast sensitivity.METHODS:This cross-sectional study was conducted in the optometry clinic of the Shahid Beheshti School of Rehabilitation on 48 students in 2021-2022.All of them had eye health and normal visual function and could have refractive errors or not.Light intensity of 4 lx was considered equivalent to photopic light condition and light intensity of 1 lx was considered to be equivalent to mesopic light condition.The amount of refractive error was checked by auto refractometer and its changes in mesopic light condition were subjectively measured.Also,visual acuity,stereopsis and contrast sensitivity(in five spatial frequencies of 1.5,3,6,12,and 18 cycles per degree),were measured first in photopic light condition and then in mesopic light condition,by Snellen control vision chart,stereo butterfly test and the M&S technology monitor test respectively.RESULTS:In the 48 student subjects with an average age of 22.69±3.56y,mean of refractive error as sphere equivalent,visual acuity and stereopsis were-1.25±1.74 diopters,0 logMAR,44.37±13.03 seconds of arc,respectively in photopic light condition while in mesopic light was equal to-1.56±1.75 diopters,0.12±0.09 logMAR and 50.62±33.35 seconds of arc,respectively.The mean of contrast sensitivity measured at spatial frequencies of 1.5,3,6,12,and 18 cycles per degree in photopic condition was equal to 2.38±0.04,2.37±0.07,2.04±0.21,1.27±0.32,0.82±0.27 logarithm of contrast sensitivity,respectively and in mesopic lighting condition was equal to 2.34±0.12,2.30±0.16,1.84±0.28,1.02±0.28,0.63±0.24 logarithm of contrast sensitivity,respectively.Statistical analysis showed a significant difference between the two lighting conditions in all evaluated variables[refractive error(P<0.001),visual acuity(P<0.001),stereopsis(P=0.008)and contrast sensitivity(P<0.001)].CONCLUSION:The refractive error of the student subjects in mesopic light condition change towards myopia,and its amount is clinically significant.Also,the examination and comparison of the factors of visual acuity,stereopsis and contrast sensitivity in these two lighting conditions show that the decrease in brightness level to the mesopic level causes a decrease in the aforementioned visual functions.
文摘AIM: To determine whether the photopic negative response(Ph NR) elicited by transient white flash on white background is characterizing for glaucoma model in rabbits.METHODS: Glaucoma was induced in twelve rabbits by subconjunctival injection of 0.05 m L of betamethasone in right eyes(each 1 m L contain betamethasone dipropionate5 mg and betamethasone sodium phosphate 2 mg).The intraocular pressure(IOP), electroretinogram(ERG) and visual evoked potential(VEP) were measured successively prior and on the 3, 7d, two weeks and four weeks postglaucoma induction. After four weeks, the animals were sacrificed and the globes were histopathologically examined.RESULTS: The IOP increased significantly after one week(P =0.0001), then it gradually returned to the control level. In ERG examination, the means of a and b wave amplitude and latency were not affected significantly.Ph NR amplitude decreased significantly within one week(P =0.0001), but its latency was not affected significantly(P =0.132). The means of VEP latency and amplitude were significantly affected after two weeks and four weeks of glaucoma induction(P =0.0001 and 0.02,respectively). The histopathologic examination of the globes showed reduced number of cells in the retinal ganglion cell layer with multiple vacuoles in the retinal nerve fibre layer.There was significant positive correlation between ganglion cell layer cells and Ph NR amplitude( r =0.8, P =0.002).CONCLUSION: The rise in IOP resulted in irreversible changes or incomplete recovery of VEP and Ph NR amplitude. Both Ph NR and VEP represented good additional tools in early diagnosis of glaucoma.
文摘I am Dr. David P Pifiero from the Department of Optics, Pharmacology and Anatomy of the University of Alicante and from the Department of Ophthalmology of Vithas Medimar （Oftalmar） and Vithas Virgen del Carmen （Qvision） hospitals in Spain.
文摘Purpose:.To evaluate the diagnostic performance of the photopic negative response (PhNR) for the detection of primary open-angle glaucoma (POAG). Methods:.Fifty-two normal subjects (52 eyes) and 173 POAG patients.(173 eyes) were studied. The PhNR was elicited using a white stimuli on a white background..The mean deviation (MD) and pattern standard deviation (PSD) of the visual field were measured using standard automated perimetry (SAP)..Spectral domain optical coherence tomography (SD-OCT).was used to measure the mean thickness of the retinal nerve fiber layer (RNFL). Results:.In the glaucoma group,.as compared to the normal group,.the amplitudes of a-waves,.b-waves and PhNR were significantly smaller (P<0.001), and the PhNR implicit time was significantly longer.(P=0.004). The MD, PSD and mean thickness of the RNFL were significantly correlated with the amplitude of the PhNR (P<0.001). The area under the receiver operating characteristic curve (AUCs) for the amplitudes of a-waves,.b-waves and PhNR were 0.853,.0.830 and 0.918, respectively. When the specificity was ≥95%, the sensitivities were 60.4%, 54.2% and 85.4% respectively. Conclusion:The PhNR amplitude was reduced even when the loss in visual field sensitivity was mild, which suggests that PhNR might be a useful indicator of early glaucoma disease.
