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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 33  |  Issue : 3  |  Page : 278-283

A cross sectional study of visual field patterns in advanced primary open-angle glaucoma


1 Department of Ophthalmology, Government Medical College, Thrissur, Kerala, India
2 Department of Ophthalmology, Government Medical College, Manjeri, Kerala, India

Date of Submission08-Dec-2020
Date of Decision19-Jan-2021
Date of Acceptance20-Jan-2021
Date of Web Publication08-Dec-2021

Correspondence Address:
Dr. Anisha Tresa Augustin
Madona, Thiruppady Lane, Mannuthy, Thrissur - 680 651, Kerala
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/kjo.kjo_200_20

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  Abstract 


Objectives: (1) To identify the patterns of visual field defects in patients with primary open-angle glaucoma (POAG) in advanced stage. (2) To identify macular split in patients with POAG in advanced stage. Materials and Methods: A cross-sectional study of 180 eyes of 160 patients within a period of 1 year was conducted. All patients with advanced POAG according to the modified Hodapp–Parrish–Anderson criteria were included in the study. A detailed examination including best-corrected visual acuity, color vision, gonioscopy, fundus examination, intraocular pressure measurement, visual field analysis using Humphrey field analyzer, and macular program was done. Results: Of the total 180 eyes, 7.2% had 0.8 cup, 67.8% had 0.9 cup, and 25% had glaucomatous optic atrophy. In the 30-2 program, 11.7% eyes had superior arcuate scotoma, 13.9% had inferior arcuate scotoma, 27.8% had double arcuate scotoma, and 46.7% had severely depressed field. In the 10–2 program, 22.8% had normal field, 26.1% had scotomas not involving fixation, and 51.1% had scotomas involving fixation. In the macular program, 63.3% had normal result, 18.3% had macular threat, and 18.3% had macular split. Conclusions: The most common field defect in the 30–2 program was severely depressed field. The most common defect in the 10–2 program was scotomas involving fixation. The macular program was normal in a majority of patients.

Keywords: Field defects, macular split, primary open-angle glaucoma


How to cite this article:
Augustin AT, Rajini K C, Sudha V. A cross sectional study of visual field patterns in advanced primary open-angle glaucoma. Kerala J Ophthalmol 2021;33:278-83

How to cite this URL:
Augustin AT, Rajini K C, Sudha V. A cross sectional study of visual field patterns in advanced primary open-angle glaucoma. Kerala J Ophthalmol [serial online] 2021 [cited 2022 Jan 19];33:278-83. Available from: http://www.kjophthal.com/text.asp?2021/33/3/278/331943




  Introduction Top


Primary open-angle glaucoma (POAG) is an adult onset, bilateral, symmetrical disease. It is one of the leading causes of blindness worldwide. The field changes in POAG are initially seen in the Bjerrum's area (10°–25° around fixation) and gradually increase according to the optic disc changes. Field defects in advanced glaucoma are diagnosed with the help of the Hodapp–Parrish–Anderson criteria [Table 1].[1]
Table 1: Hodapp-Parish-Anderson criteria

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Macular split is a field defect observed in the advanced stage. Split macular fixation is defined as one of the four points abutting fixation on the macular program having a sensitivity of a single digit (<10, normal threshold being in the 30s) with an adjacent point on the same side of fixation in another quadrant also being <10 [Figure 1].
Figure 1: Macular split

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Studies published so far have attempted to compare various methods to assess the progression of field defects.

This study aims to analyze the different patterns of visual field defects in advanced POAG and also to document the occurrence of macular split in these cases.


  Materials and Methods Top


Study design

Cross-sectional study.

Study setting

Department of ophthalmology of a tertiary care hospital in Kerala.

Study population

Patients attending the glaucoma clinic of department of ophthalmology and diagnosed as having advanced POAG.

Inclusion criteria

Patients with advanced POAG according to the modified Hodapp–Parrish–Anderson criteria.

Exclusion criteria

  1. Early stages of POAG
  2. Secondary glaucoma
  3. Closed-angle glaucoma.


Sample size calculation

For the significance level, α = 5%



where P = prevalence = 38% (84)

q = 1 − p

d = precision = 0.2 p



Sample size = 160

Study Period

One year.

Methodology

Ours was a hospital-based cross-sectional study. 180 eyes of 160 patients diagnosed as having advanced POAG were selected based on the inclusion and exclusion criteria. These patients are on follow-up at the glaucoma clinic at our institution. Informed consent was obtained from all patients and details of the study were explained. Approval was obtained from the institutional ethics committee and the institutional review board.

Patient biodata and sociodemographic details were recorded. A brief medical and ophthalmic history was taken and patients were asked to fill up the study pro forma. Patients were then clinically evaluated as follows:

  1. Visual acuity using Snellen's or E chart
  2. Color vision using Ishihara chart
  3. Pupils were assessed. Swinging flashlight test was done to look for relative afferent pupillary defect
  4. Slit-lamp examination using Haag–Streit slit lamp
  5. Intraocular pressure by applanation tonometry
  6. Direct ophthalmoscopy using a Keeler direct ophthalmoscope
  7. Indirect ophthalmoscopy
  8. Indirect gonioscopy using Goldmann single-mirror gonioprism
  9. Slit-lamp biomicroscopy using Volk 90D lens
  10. Visual field tested on Humphrey Field Analyzer II (SITA standard) using 30–2, 10–2, and macular programs.


Patients were selected till sample size was attained.

Study variables

  1. Age
  2. Sex
  3. Duration
  4. Family history
  5. Vision
  6. Color Vision
  7. Pupil
  8. Cup–disc ratio (CDR)
  9. Intraocular pressure
  10. 30-2
  11. 10-2
  12. Macular program


Patient data were recorded on a pro forma, coded, and entered into a Microsoft Excel spreadsheet. Statistical Package for the Social Sciences (SPSS Version 20) (IBM Corp. Released 2011. IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp) was used for statistical analysis. Variables were represented using frequency and percentage analysis.


  Results Top


This study included 180 eyes of 160 patients. The following were our observations:

  1. Age: The age-wise distribution of patients is shown in [Table 2]. Majority of patients were above the age of 55 years
  2. Sex: Males formed a major share of the patients in this study
  3. Family history: Only 13% of the subjects had a positive family history
  4. Vision: Most of our patients had vision visual acuity more than 6/12 with maximum number in 6/9 category as shown in [Table 3]
  5. Color vision: 62.8% of eyes had retained normal color vision whereas 37.2% of eyes had defective color vision
  6. Pupils: A normal brisk pupillary reaction was observed in a majority of patients and only 26.7% of our patients with advanced glaucoma had a relative afferent pupillary defect
  7. CDR: The distribution of cup to disc ratio is shown in [Table 4] and [Figure 2]
  8. Intraocular pressure was <12 in 93 out of 180 eyes
  9. 30-2: The results showed that most patients with advanced glaucoma had a severely depressed field [Table 5] and [Figure 3]
  10. 10–2: 51% of the eyes had scotomas involving fixation in the 10–2 program. [Table 6] and [Figure 4]
  11. Macular program: A normal study was obtained in 63% of the eyes studied and only a minority had a macular split [Table 7] and [Figure 5]
  12. The comparative data between the CDR and the field patterns are summarized in [Table 8], [Table 9], [Table 10].
Table 2: Distribution of age

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Table 3: Distribution of vision

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Table 4: Distribution of cup-disc ratio

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Figure 2: Distribution of Cup–disc ratio

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Table 5: Distribution of results of 30-2 program

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Figure 3: Distribution of results of 30–2 program

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Figure 4: Distribution of results of 10–2 program

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Table 6: Distribution of results of 10-2 program

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Table 7: Distribution of results of macular program

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Figure 5: Distribution of results of macular program

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Table 8: Results of 30-2 versus cup-disc ratio

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Table 9: Results of 10-2 versus cup-disc ratio

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Table 10: Results of macular program versus cup-disc ratio

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  Discussion Top


In this study, we have analyzed the various visual field patterns in advanced POAG. We analyzed 180 eyes of 160 patients who satisfied the inclusion criteria for advanced POAG. The progression of field changes in chronic open-angle glaucoma has already been described. Different patterns of visual defects are seen depending on the optic disc damage, though the field defects cannot be always be predicted from the appearance of the optic disc. Here, we have examined the visual fields and the clinical profile of patients with advanced POAG.

Age: Most patients in our study were above the age of 55 years. The minimum age was 28 and the maximum age was 85 years. A study conducted by Cedrone et al. states that one-third of the population between the age group of 40–75 years suffered from open-angle glaucoma.[2] Similar results were obtained in a study conducted by Kroese et al.[3]

Sex: Males formed a majority of patients in our study. Around 74% were male and 26% were female. In a study conducted by Rudnicka et al., it was found out that men are more likely to develop open-angle glaucoma than females[4]

Family history: Though family history is a very significant risk factor for development of POAG, it was positive in only 13.3% of eyes with advanced disease

Vision: Most of our patients had vision visual acuity more than 6/12 with maximum number in 6/9 category. Visual acuity was largely preserved in patients with advanced disease even though their visual fields were constricted. This is due to the fact that the retinal ganglion cells in the papillomacular area are preserved till the end. Vision is affected when these are also damaged as in 18 eyes in our study where the vision was less than 6/60. This has been reported in a study by Asaoka[5]

Color vision: 62.8% of eyes had retained normal color vision whereas 37.2% of eyes had defective color vision. It was mainly those eyes with glaucomatous optic atrophy that demonstrated defective color vision. A study conducted by Niwa et al. confirms that color vision especially blue–green defects are associated with glaucoma[6]

Pupils: A relative afferent papillary defect was seen in 26.7% and they were sluggish in 5% of eyes. 68.3% of eyes had a normally reacting pupil. The presence of a relative afferent papillary defect denotes asymmetric damage to the optic nerve and is commonly seen in the late stages of glaucoma.[7] A study conducted by Page et al. opined that quantitative analysis of RAPD by neutral density filter correlates better with visual field loss. In our study, only swinging torchlight examination was done

Perimetry and cup–disc ratio.

  1. 30-2: In this study, 46% of eyes had severely depressed fields followed by double arcuate scotoma. Thirty-four percent of eyes with severely depressed fields had a cup–disc ratio of 0.9 and 89% of eyes had glaucomatous optic atrophy. 13.9% of eyes had inferior arcuate scotoma and 11.7% had superior arcuate scotoma
  2. 10–2: In our study, 51.1% of eyes had scotomas involving fixation whereas 22.8% had a normal field in 10–2 program. Most eyes with glaucomatous optic neuropathy had scotomas involving fixation (82.2% of eyes). In the late stages, the central vision gets affected and this is better picked up with a 10–2 field analysis.[8] Even in very advanced cupping, 4.4% had a normal field. This is probably due to remaining unaffected ganglion cells in the macula
  3. Macular program: Around 63.3% of eyes had a normal macular program. 24.4% of eyes with advanced cupping had a normal program in spite of having severely depressed fields on 30–2 program. Only 18% of total sample had macular split. This could be explained by the fact that the macular program tests only the central 16 points around 5 degrees of fixation which would be the last to be lost. Furthermore, this program would be less tiring for the patient and less time-consuming and hence the patient's response would be more accurate



  Conclusions Top


  • The most common field defect in 30–2 program was a severely depressed field
  • The maximum result in 10–2 program was scotomas involving fixation
  • Macular program was normal in a majority of patients.


Limitations of the Study

Our sample size was limited as it was a time bound study. A larger sample size over a longer period of time would be more beneficial. Furthermore, color vision was analyzed using the Ishihara chart. A detailed evaluation of the type of color vision affected in advanced glaucoma would be a better analysis. In patients with bilaterally defective color vision, congenital color blindness was not ruled out. Relative afferent pupillary defects should be quantified with a neutral density filter. This could not be done in our study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
European Glaucoma Society Terminology and Guidelines for Glaucoma, 4th Edition-Part 1 Supported by the EGS Foundation. Ageing and ocular surface immunity. Br J Ophthalmol 2017;101:1-72.  Back to cited text no. 1
    
2.
Cedrone C, Mancino R, Cerulli A, Cesareo M, Nucci C. Epidemiology of primary glaucoma: Prevalence, incidence, and blinding effects. Prog Brain Res 2008;173:3-14.  Back to cited text no. 2
    
3.
Kroese M, Burton H, Vardy S, Rimmer T, McCarter D. Prevalence of primary open angle glaucoma in general ophthalmic practice in the United Kingdom. Br J Ophthalmol 2002;86:978-80.  Back to cited text no. 3
    
4.
Rudnicka AR, Mt-Isa S, Owen CG, Cook DG, Ashby D. Variations in primary open-angle glaucoma prevalence by age, gender, and race: A Bayesian meta-analysis. Invest Ophthalmol Vis Sci 2006;47:4254-61.  Back to cited text no. 4
    
5.
Asaoka R. The relationship between visual acuity and central visual field sensitivity in advanced glaucoma. Br J Ophthalmol 2013;97:1355-6.  Back to cited text no. 5
    
6.
Niwa Y, Muraki S, Naito F, Minamikawa T, Ohji M. Evaluation of acquired color vision deficiency in glaucoma using the Rabin cone contrast test. Invest Ophthalmol Vis Sci 2014;55:6686-90.  Back to cited text no. 6
    
7.
Page CJ, Merritt JC, Evans B. Relative afferent pupillary defects in primary open-angle glaucoma-five years' experience. J Natl Med Assoc 1985;77:979-84.  Back to cited text no. 7
    
8.
Rao HL, Begum VU, Khadka D, Mandal AK, Senthil S, Garudadri CS. Comparing glaucoma progression on 24-2 and 10-2 visual field examinations. PLoS One 2015;10:e0127233.  Back to cited text no. 8
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10]



 

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