Clinical science Visual field defect classification in the Zhongshan Ophthalmic Center–Brien Holden Vision Institute High Myopia Registry Study Xiaohu Ding,1 Robert T Chang,1,2 Xinxing Guo,1 Xing Liu,1 Chris A Johnson,3 † Brien A Holden,4, Mingguang He1 ▸ Additional material is ABSTRACT myopia is rapidly becoming a major public health published online only. To view Purpose To describe a new combined myopia and problem.4 please visit the journal online fi fi (http://dx.doi.org/10.1136/ glaucoma visual eld classi cation system in order to The relationship between high myopia and bjophthalmol-2015-307942). report the visual field defects in a population of mostly POAG has been explored extensively in prior young Chinese high myopes aged 7–70 years. studies.5 However, accurate diagnosis of glaucoma fi 1 Methods A total of 1434 visual elds (including in the setting of high myopia is a challenge in clin- State Key Laboratory of confirmatory repeats of abnormal defects) from 487 high ical practice for two major reasons: (1) High Ophthalmology, Zhongshan ≤− Ophthalmic Center, myopes (sphere 6.0 D) were analysed from the myopia can cause tilted optic discs, large peripapil- Sun Yat-sen University, prospective Zhongshan Ophthalmic Center–Brien Holden lary atrophy obscuring the disc edge and shallow Guangzhou, China Vision Institute (ZOC–BHVI) High Myopia Registry Study. cupping without shifting of the vessels nasally, 2 Department of The predefined classification definitions covering high making the subjective interpretation of glaucomat- Ophthalmology, Byers Eye fi Institute at Stanford University, myopia and glaucoma categories were: normal, enlarged ous excavation more dif cult. (2) Although the Palo Alto, California, USA blind spot, abnormal suspect and abnormal with nine diagnosis of glaucoma relies upon characteristic 3Department of Ophthalmology subtypes. Two independent graders reviewed the first optic nerve cupping with associated progressive and Visual Sciences, University 150 of 1434 fields for initial grading calibration and the visual field loss, myopic degeneration can also of Iowa, Iowa City, Iowa, USA 4 remaining 1284 fields were used to assess intergrader cause similar glaucomatous-like visual field Brien Holden Vision Institute, 67 University of New South Wales, agreement. For the percentage distribution of visual defects. Therefore, patients need to be followed 8 Sydney, New South Wales, fields, the repeats and unreliable fields were excluded, over time to confirm true glaucoma progression. Australia leaving 894 fields. There is little information in the literature describ- Results The intergrader agreement of this combined ing the overall clinical characteristics of high Correspondence to fi κ fi Dr Robert T Chang, classi cation system was a value of 0.61 (95% CI myopes with visual eld defects or any prospective Byers Eye Institute at Stanford, 0.59 to 0.63). Among the 894 unique fields, the most data on how or if myopic defects change over time. 2452 Watson Ct, common visual field was normal at 33.7% followed by We were interested in determining how often Palo Alto CA 94303, USA; enlarged blind spot at 25.6%. The per cent of ‘arcuate- Chinese myopes have visual field defects that mimic [email protected] like’ field defects (combining nasal step, early arcuate glaucoma, particularly since many of those defects †Deceased 27 July 2015 and advanced arcuate) was 16.1% with advanced in young myopes may be minimally progressive and arcuate at 3.4%. not glaucomatous.9 Received 12 October 2015 Conclusions A proposed combined visual field In the present study, we first propose a broader Revised 15 February 2016 classification for high myopia and glaucoma combined classification system of visual field Accepted 22 February 2016 Published Online First demonstrates acceptable intergrader agreement. A total defects in high myopes to include both high 31 March 2016 of 16.1% of defects in young high myopes were found myopia and glaucoma types. After reporting the to mimic classic glaucomatous defects. These subjects intergrader agreement, we describe the baseline are being followed prospectively to assess which ones percentages of each field defect type in a large will progress to differentiate myopic from glaucomatous group of Chinese high myopes aged 7–70 with a field defects. median age of 17.4 years. The data collected, including visual fields, is part of an ongoing ZOC– BHVI High Myopia Registry Study that is designed INTRODUCTION to understand the natural history and pathogenesis Myopia morbidity continues to increase substan- of myopic retinopathy, initiated in November 2011 tially worldwide,1 especially in East Asians.2 in Guangzhou, China. Myopia can be corrected by spectacles, contact lens, or various intraocular or laser refractive sur- METHODS geries to achieve good vision. However, in high Ethics approval was obtained from the Zhongshan myopia, defined as worse than or equal to −6 diop- Ophthalmic Center Ethics Review Board. The tres sphere and also known as degenerative myopia, study was conducted in accordance with the tenets sight-threatening complications increase with many of the World Medical Association’s Declaration of potentially blinding conditions, such as myopic Helsinki. Written informed consent was obtained degenerative retinopathy, macular scars, increased from all participants, or their parents or legal guar- primary open-angle glaucoma (POAG) and more dians if their age was <18 years. 3 To cite: Ding X, Chang RT, frequent retinal detachment. Unlike cataract or Guo X, et al. Br J age-related macular degeneration, which mainly Study population Ophthalmol affect the elderly population, high myopia also A longitudinal observational high myope registry – 2016;100:1697 1702. affects many young adults of working age; thus study was initiated in Guangzhou in 2011 and is Ding X, et al. Br J Ophthalmol 2016;100:1697–1702. doi:10.1136/bjophthalmol-2015-307942 1697 Clinical science expected to run until 2021. Subjects with high myopia, defined as worse than or equal to −6 dioptres sphere (not spherical equivalent) in both eyes, were recruited from both optometric clinic and a previous community screening population study in order to have more subjects older than 50 years.10 At baseline, a total of 895 participants were eligible and enrolled in the regis- try. However, only 487 subjects had visual field data. Baseline data collected in the high myopia registry included: cycloplegic refraction, best-corrected visual acuity, ocular biom- etry, external motility and slit lamp exam, lens opacity by the Lens Opacities Classification System (LOCS III) grading scale, intraocular pressure (IOP) measurement by Goldmann applana- tion, standard automatic perimetry, B-scan ultrasound, digital stereo fundus photography (Canon CX-1), autofluorescence (Heidelberg Spectralis) and spectral domain optical coherence tomography (SD-OCT Optovue). Refraction was performed with an autorefractor (Topcon KR-8800) after cycloplegia. Ocular biometric parameters including axial length were obtained by optical low-coherence reflectometry (Lenstar LS-900, Haag-Streit AG). Figure 1 The schema of our recruitment. Visual field examination A total of 487 subjects underwent bilateral standard automatic perimetry (Zeiss Humphrey Visual Field 750i, Carl Zeiss the established criteria to determine final percentages reported Meditec, Dublin, California, USA) on a separate return visit, from the unique 894 fields in which repeat or unreliable fields using the 24-2 Swedish interactive threshold algorithm (SITA) had been removed. A total of 167 unreliable fields (13%) were fast, white-on-white, performed on a single machine. All visual removed. If the original and repeat field were both reliable, then fi elds were conducted in a single dark room without distraction the field with fewer false positives was chosen or fewer fixation (ambient light <5 lux) with a trained technician who explained losses if the false positives were the same. Thus, 167 unreliable to all subjects how to complete the test reliably. Each subject and 373 repeat visual fields were removed, arriving at the 894 fi had a short demonstration test before commencing the of cial visual field total for analysis (figure 1). examination. During the test, the technician also monitored the subject’s eye movement, and made adjustments as necessary to maintain proper fixation. Unreliable fields, defined as reach one Statistical analysis – of three criteria: false positive ≥15%, false negative ≥33% and Median, range and 25th 75th percentile were used to describe fixation loss ≥33%, were repeated immediately (up to two the non-normal distribution parameters. The agreement κ times) as well as any abnormal fields. From November 2011 to between two graders was assessed by , whose values of >0.7 August 2012, a total of 1434 visual fields (including repeats of are generally considered excellent and between 0.4 and 0.7 are abnormals) from 487 patients were available for our current considered as moderate. p<0.05 was considered statistically sig- fi visual field analysis, the outline of the recruitment was shown in ni cant. All statistics were performed using STATA (V.12.0, figure 1. Stata, College Station, Texas, USA). Visual field classification system and grading RESULTS In order to include visual field defect types associated with high Among the 487 participants, 229 (47.0%) were male and 258 myopia, new visual field grading criteria were drafted, consisting (53.0%) were female. The median age was 17.4 years, range of four major types: normal, enlarged blindness spot (at least 7–70 years, the 25% percentile was 13.3 years and 75% per- two abnormal edge point around the blind spot), suspicious for centile was 28.1 years. The median refraction was −8.6 D, range abnormal (minimum criteria for a defect but no pattern) and −6to−35 D, 25% and 75% percentiles were −7.4 and definitely abnormal (figure 2). The grading criteria for glau- −11.0 D, respectively. The median axial length was 27.2 mm, comatous defects were adapted from the Ocular Hypertension range 23.8–32.0 mm and the 25% and 75% percentiles were Treatment Study visual field criteria: nasal step, early arcuate, 26.3 and 28.1 mm, respectively (table 1).