A Study On Correlation Of Visual Impairment With CpRNFL Thickness And GCIPL Thickness In TAO-Compressive Optic Neuropathy Patients

Background and purposeCompressive optic neuropathy(CON)can be caused by thyroid-associated(TAO)ophthalmology,which impairs visual function severely and leads to a decline in the quality of life of patients.The thicknesses of ganglion cell-inner plexiform layer(GCIPL)and circumpapillary retinal nerve fiber layer(CPRNFL)represent structural damage of retinal ganglion cells and axons after optic nerve impariment,respectively.It is reported that Optical coherence tomography(OCT)has played a key role in the early diagnosis and the follow-up of ophthalmic diseases like glaucoma,and optic disk and macular leision.The correlation of cpRNFL and GCIPL thickness in TAO-CON patients using OCT with visual acuity impairment,and the impact of the former on visual acuity outcome were analyzed in this research,which were reported as follows.Clinical data and methods1 Clinical data94 TAO patients(146 eyes)with complete clinical data,diagnosed and treated at the clinic and ward of our treatment group of Department of Ophthalmology,First Affiliated Hospital of Zhengzhou University during January 2018 and July 2020,were enrolled.Among them,52 patients were bilateral and 42 patients were unilateral.There were 42 males(61 eyes)and 52 females(85 eyes).Their age ranged from 23 to 74 years old,and the average age was(58±8)years old.A total of 19 cases of TAO-NCON patients(28 eyes)and 49 normal subjects(49 eyes)with comparable ages and gender were selected as the control group.2 Research methodsProspective study.According to the BCVA,TAO-CON patients were divided into NLP～0.1、0.1～0.3、0.3～1.0 visual(mild,moderate and severe visual impairment)groups.All subjects underwent routine eye examination,bilateral best corrected visual acuity(BCVA)and OCT to detect circumpapillary RNFL thickness,rim area,disk area,average C/D ratio,vertical C/D ratio,cup volume,macular GCIPL thickness and inner limiting membrane-retinal pigment epithelium(ILM-RPE)thickness.The CON patients who received regular treatment(35 subjects with 41 eyes)were followed up over 6 months.Data of their BCVA and other ophthalmic inspection were included.The BCVA at last follow-up was regarded as visual outcome.The Kruskal Wallis nonparametric test was used to compare the differences of cpRNFL thickness,rim area,disk area,average C/D ratio,vertical C/D ratio,cup volume,macular GCIPL thickness and ILM-RPE thickness,and visual prognosis among the mild,moderate and severe visual impairment groups of TAO-CON,the TAO-NCON group and the normal control group.The correlation of visual prognosis with cpRNFL and GCIPL thickness were analyzed by Spearman rank correlation analysis.P<0.05 was considered to be statistically significant.Results1.The average cpRNFL thickness in the mild,moderate,severe visual impairment groups of TAO-CON,and the TAO-NCON group was significantly higher than that in the normal control group.The average cpRNFL thickness among the mild,moderate,severe visual impairment groups of TAO-CON was pairwise compared,and the differences were also statistically significant(all P<0.005).The heavier the compression was,and the thicker the cpRNFL became,the worse the visual acuity was.2.The average GCIPL thickness in the severe and moderate visual impairment group of TAO-CON was significantly lower than that in the mild visual impairment group of TAO-CON,the TAO-NCON group and the normal control group,and the differences were statistically significant(P<0.005).3.The visual acuity of TAO-CON patients with mild visual impairment is likely to be restored to normal,while the visual acuity of those with moderate or severe visual impairment is difficult to be restored to normal.The average thickness of cpRNFL and GCIPL in TAO-CON patients with obvious postoperative visual acuity improvement was about 8%thicker and 8%thinner than that of the normal control group.4.The prognostic BCVA(LogMAR)of TAO-CON patients was strongly negatively correlated with GCIPL thickness in macular area(r=-0.928,P=0.008).Conclusion1.The changes of thickness of cpRNFL and GCIPL in TAO-CON patients were correlated with the degree of visual impairment;2.The thickness of GCIPL of TAO-CON patients was closely related to the visual prognosis.