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- DOI 10.18231/j.ijceo.2020.040
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CrossMark
- Citation
Optical coherence tomographic assessment of disc changes and automated perimetric assessment of visual field changes after glaucoma filtration surgery
- Author Details:
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Kumaresh Chandra Sarkar
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Piyali Sarkar *
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Shashwat Bhattacharyya
Abstract
Purpose: The study was conducted to find out the topographic changes of disc, macular thickness, visual field, and intra-ocular pressure (IOP) after trabeculectomy in different age and sex using Optical Coherence Tomography (OCT) machine, automated perimeter and Goldman applanation tonometer respectively.
Materials and Methods: It was a prospective, interventional case-series conducted at the glaucoma clinic at Regional Institute of Ophthalmology, Kolkata from March 2010 to August 2011. Patients of primary open angle glaucoma who fulfilled the inclusion criteria. The trabeculectomy surgeries were done by a single surgeon. The disc changes, macular thickness, IOP and visual field changes were measured before and after trabeculectomy. Preoperative OCT images of disc and macula, visual field testing by Humphrey automated perimeter and IOP by Goldman applanation tonometry were done/within 3 months prior to surgery and same investigations had been done postoperatively within 2 to 3 months after surgery. Data was collected in a standard data collection form and analysis was done by paired t-test.
Results: Significant visual field (mean deviation-MD & pattern standard deviation-PSD in decibel) changes were seen but the nerve fiber thickness in the disc and macula were not increased. Significant reduction of IOP was found after trabeculectomy.
Conclusions: Significant visual field (MD& PSD) changes were found after trabeculectomy in early glaucoma patients but disc and macular changes were found to be insignificant.
Introduction
Glaucoma is a progressive optic neuropathy with characteristic appearance of the optic disc and specific pattern of visual field defect that is associated frequently but not invariably with raised intraocular pressure. As the visual loss is often symptomless it goes unnoticed and undiagnosed in many cases. Reversal of optic disc cupping following intraocular pressure (IOP) reduction is a well-known phenomenon in congenital[1], [2] and juvenile[3], [4] glaucoma. Although it has been reported in adult patients also, but the results of these studies seem conflicting. The inconsistent outcomes in adults may be due to the stage of disease, the amount of IOP reduction, and the age of the patient. The clinical relevance of ‘reversal' has not been established with certainty, although reports[5], [6] have suggested that there may be an associated improvement of visual function that corresponds to this improvement in disc appearance.
Glaucoma is a second common cause of blindness in the world after cataract. It was estimated to affect 60.5 million people in the world and 11.9 million in India in the year 2010.[7], [8] It accounts for 12.3 percent of blindness worldwide and 7.9 percent of total blindness in India.[9], [10]
The structural changes of ONH precede visual field loss in glaucoma,[11] although in recent times many investigators have found a structure–function dissociation[12], [13] and unbiased studies have found that the first signs of conversion or progression may appear in either structural or functional measures.[14] So, most clinicians consider that the progressive changes in either ONH structure or function may need intervention for further lowering of IOP. Clinical examination of the optic disc is not enough to reproduce[15], [16] and sometimes, subtle changes in the optic nerve head (ONH) topography and visual field measurement may be very difficult to assess. Backward bowing of the lamina cribrosa is caused by damage of the ONH by mechanical theory that postulates raised of IOP. [17], [18] The IOP reduction may theoretically prevent this back bowing, and it maybe the mechanism of reversal of optic disc cupping even in adults. Release of pressure on the nerve fibres passing through the lamina may also result in changes in neuroretinal rim (NRR) thickness and visual field after IOP reduction.
Our study was done to measure ONH topography, macular thickness and visual field changes by OCT and automated perimeter respectively in order to demonstrate any structural improvement following IOP reduction after trabeculectomy in adult patients.
Materials and Methods
The study was a prospective, interventional case series. It was conducted to evaluate the patients at the Glaucoma Clinic at the Regional Institute of Ophthalmology, Medical College, Kolkata during March 2010 to August 2011. The patients were counseled and informed consent was taken for participation in the study. Detailed history and thorough ocular examination were taken. Whether patient had any risk factors like family history of glaucoma, ocular trauma, past eye surgery and other ocular morbidity were determined by personal interview. The visual acuity of each eye; both with and without corrections were noted. Refraction was carried out manually using streak retinoscope followed by subjective corrections. Anterior segment was evaluated both by diffuse light and slit-lamp. The subjects were selected for intervention after proper diagnosis. The patients who were willing to participate and fulfilled all the inclusion criteria after full ophthalmological evaluation were included. The patients with extreme age, very sick, unwilling to follow-up, failed to give consent, patients having diabetic retinopathy, age related macular degeneration, cystoid macular edema, macular dystrophy, central serous retinopathy, patients having advanced cataract and ocular pathology which can affect visual field and nerve fiber thickness other than glaucoma were not included in the study.
The diagnosis of primary open angle glaucoma was done by detailed optic disc evaluation with slit lamp biomicroscope and angle evaluation by gonioscope. Visual field and disc and RNFL changes were evaluated by automated perimeter (Humphrey Field Analyzer II) and OCT (Carl.Ziess-Stratus OCT) respectively. All the procedures were done before and after glaucoma surgery. The patients were prepared for filtration surgery. And subsequent follow up was done and findings of disc and visual field changes were recorded.
Statistical analysis
Paired t tests were used to analyze NRR (ONH) thickness, macular thickness, IOP and visual field changes in every patient. All analyses were performed with SPSS software (version 17) and p values < 0.05 were considered to be statistically significant.
Results
This prospective study was conducted to evaluate disc, macular thickness, visual field and IOP changes. 49 eyes of 41 patients were included in this study. The study showed slightly male (53%) preponderance. The average age of the patient was 50.18 ± 11.36 years. The average age of male and female patients were 47.42 ± 12.81 and 53.30 ± 12.17 years respectively.
The changes in the average thickness of NRR were found significant in nasal and temporal quadrant ([Table 1]). The IOP reduction was statistically significant irrespective of age and sex ([Table 2], [Table 3]). The visual field (MD and PSD) changes were statistically significant in older age group (age >50 years, p = 0.095& p== 0.0003) and in female patients (p=0.006 & p=0.00001). But pattern standard deviation (PSD) was only statistically significant in younger age group (p = 0.0002) ([Table 2]). It had been found that, cup/disc ratio changes were only statistically significant in older age group (p= 0.002) ([Table 2], [Table 3]).
Patients aged >50 years, the MD and PSD of the preoperative visual fieldwere-12.37±4.10 dB and 7.44±1.82dB, respectively. The MD and PSD of the postoperative visual field were -10.99±6.46 dB and 6.75±2.15 dB, respectively. Patents aged <50 years, the MD and PSD of the preoperative visual field were-11.48±4.17dB and 7.87±1.89 dB, respectively. The MD and PSD of the postoperative visual field were -10.34±8.09 dB and 7.19±1.97 dB, respectively ([Table 2]).
Similarly, in male patients, the MD and PSD of the preoperative visual field were-12.07±4.45dB and 7.33±1.8dB, respectively. The MD and PSD of the postoperative visual field were -11.86±8.22dB and 6.84±2.11dB, respectively. In female patients, the MD and PSD of the preoperative visual field were-11.74±3.71dB and 8.021±1.77dB, respectively. The MD and PSD of the postoperative visual field were-9.38±5.58dB and 7.12±1.90dB, respectively, ([Table 3]).
| Variable | Preoperative NRR thickness (μm) | Postoperative NRR thickness (μm) | Mean difference (μm) | P value |
| Superior | 69.02±22.25 | 68.24±25.82 | -0.75±5.40 | 0.322 |
| Nasal | 59.63±18.92 | 58.06±19.20 | -1.53±3.34 | 0.0015 |
| Inferior | 45.86±11.66 | 44.48±13.15 | -1.40±16.52 | 0.282 |
| Temporal | 51.10±15.28 | 50.39±8.08 | -0.71±18.77 | 0.019 |
| Macular thickness | 184.02±21.03 | 183.14±19.57 | -0.88±-0.60 | 0.133 |
| Age >50 years:(n=24) | ||||
| Variable | Pre op value | Post op value | Mean difference | P value |
| IOP (mmHg) | 27.67±5.58 | 14.08±3.87 | -13.58± 2.93 | 0.00000 |
| Cup/Disc ratio | 0.78±0.104 | 0.80±0.122 | 0.02± 0.02 | 0.002 |
| VF (MD) dB | 12.37±4.10 | 10.99±6.46 | 1.38± 3.87 | 0.095 |
| VF (PSD) dB | 7.44±1.82 | 6.75±2.15 | -0.69± 0.80 | 0.0003 |
| Macular Thickness | 185.25±22.72 | 184.58±20.98 | 173.09± 4.90 | 0.330 |
| Age <50 years: (n=25) | ||||
| Variable | Pre op value | Post op value | Mean difference | P value |
| IOP (mmHg) | 27.16±4.48 | 13.92±4.58 | -13.24± -1.05 | 2.220 |
| Cup/Disc ratio | 0.77±0.10 | 0.71±0.23 | -0.06± -3.14 | 0.182 |
| VF (MD) dB | -11.48±4.17 | 10.34±8.09 | 1.10± 5.55 | 0.330 |
| VF (PSD) dB | 7.87±1.89 | 7.19±1.97 | -0.67± 0.79 | 0.0002 |
| Macular Thickness | 182.84±19.21 | 183.76±18.07 | -1.08± -1.15 | 0.186 |
| Male: (n=24) Average age of the male patients was 47.42±12.81 year. | ||||
| Variable | Pre op value | Post op value | Mean difference | P value |
| IOP (mmHg) | 27.08±4.67 | 13.58±4.16 | -13.50±2.54 | 0.00000, |
| Cup/Disc ratio | 0.78±0.104 | 0.795±0.130 | 0.005±0.037 | 0.434 |
| VF (MD) dB | -12.07±4.45 | -11.86±8.22 | 0.989±7.14 | 0.486 |
| VF (PSD) dB | 7.33±1.8 | 6.84±2.11 | -0.488±0.738 | 0.002 |
| Macular Thickness | 185±18.43 | 184.15±16.53 | -0.84+3.97 | 0.288 |
| Female: (n=25) Average age of the female patients was 53.30± 12.17 year. | ||||
| Variable | Pre op value | Post op value | Mean difference | P value |
| IOP (mmHg) | 27.79±5.06 | 14.48±4.133 | -13.3±3.12 | 0.059 |
| Cup/Disc ratio | 0.77±0.10 | 0.72±0.233 | -0.05±0.22 | 0.272 |
| VF (MD) dB | -11.74±3.71 | -9.38±5.58 | 2.37±3.69 | 0.006 |
| VF (PSD) dB | 8.021±1.77 | 7.12±1.90 | -0.89±0.79 | 0.00001 |
| Macular Thickness | 182.91±23.32 | 182.00±21.94 | -0.91±4.15 | 0.303 |
Discussion
This study evaluated the NRR thickness of disc and macular thickness changes as measured by OCT before and after trabeculectomy. The visual field changes were measured by Humphrey automated perimeter.
The study done by Erol Yildirim, Ahmed H. Bilge, Sami Ilker,[19] they observed an improvement in visual field in 75% of patients. Considering the whole threshold visual field improvement and deterioration, rates were 62.5% and 37.5% respectively. In present study showed no threshold visual field improvement.
Kotecha et al.[20] observed a significant increase in rim area and rim volume at 2 years after surgery. Segmental analysis showed a significant change in rim volume in the nasal, inferonasal, supero-nasal, and supero-temporal sectors. The present study showed significant optic disc changes in nasal and temporal quadrants but no improvement of NRR thickness in ONH with significant reduction of IOP.
Ali Aydin et al.[21] showed the mean MD and PSD of the preoperative visual field were −11.3 ± 9.2 dB and 8.2 ± 4.2 dB, respectively and the mean MD and PSD of postoperative visual field were −10.6 ± 8.1 dB and 7.8 ± 4.5 dB, respectively. These differences were not statistically significant (P = 0.43 and P = 0.34, respectively). The present study showed that the visual field (MD and PSD) changes was statistically significant in female (p=0.006 & p=0.00001) and elderly group (age>50years, p = 0.095 & p== 0.0003).
N Raghu et al.[22] observed a significant increase inferior RNFL (P=0.038) thickness. No significant change was found in other ONH parameters. Present study showed that NRR thickness changes was significant in nasal and temporal quadrants. (p =0.0015 and p=0.019)
Aachal Kotecha et al.[23] showed that the ONH and VF sensitivity changes were seen in only a small proportion of eyes. In the present study, optic disc changes were significant in nasal & temporal quadrants and VF (MD& PSD) changes was also significant in elderly age group and in female patients with significant reduction of IOP.
Conclusion
Significant visual field (MD & PSD) changes were found after trabeculectomy in early glaucoma patients but disc and macular changes were found to be insignificant. The changes are yet to be evaluated whether they have any clinical significance in long-term follow-up.
Limitations of the study
Large sample size and long-term follow up is essential to assess clinical significance of changes of ONH and visual field. The recovery of patients may be hindered in advanced glaucomatous condition and old age.
Source of Funding
None.
Conflict of Interest
There are no potential, perceived, or real competing and/or conflicts of interest among authors regarding the article.
References
- Meirelles SHS, Mathias CR, Bloise RR, Stohler NSF, Liporaci SD, Frota AC. Evaluation of the Factors Associated With the Reversal of the Disc Cupping After Surgical Treatment of Childhood Glaucoma. J Glaucoma. 2008;17(6):470-3. [Google Scholar]
- Yasuda M, Ando A, Otsuji T, Fukui C, Matsumura M. Improvement of the topographic parameters of the optic discs after trabeculotomy in two patients with developmental glaucoma. Eye. 2006;20(1):132-4. [Google Scholar]
- Leung CK, Woo J, Tsang MK, Tse KK. Structural and functional recovery in juvenile open angle glaucoma after trabeculectomy. J Pediatr Ophthalmol Strabismus. 2009;46(6):372-5. [Google Scholar]
- Wu SC, Huang SC, Kuo CL, Lin KK, Lin SM. Reversal of optic disc cupping after trabeculotomy in primary congenital glaucoma. Can J Ophthalmol. 2002;37(6):337-41. [Google Scholar]
- Tsai CS, Shin DH, Wan JY, Zeiter JH. Visual Field Global Indices in Patients with Reversal of Glaucomatous Cupping after Intraocular Pressure Reduction. Ophthalmol. 1991;98(9):1412-9. [Google Scholar]
- Leung CKS, Woo J, Tsang MK, Tse KK. Structural and functional recovery in juvenile open angle glaucoma after trabeculectomy. Eye. 2006;20(1):132-4. [Google Scholar]
- Quigley HA. The number of people with glaucoma worldwide in 2010 and 2020. Br J Ophthalmol. 2006;90(3):262-7. [Google Scholar]
- Jacob A, Thomas R, Koshi SP, Braganza A, Muliyil J. Prevalence of primary glaucoma in an urban south Indian population. Indian J Ophthalmol. 1998;46(2):81-6. [Google Scholar]
- Resnicoff S, Pascolini D, Etya , Ale. Global data on visual impairment in the year 2002. Bull World Health Organ. 2004;82:844-5. [Google Scholar]
- . National survey on blindness &visual outcome after cataract surgery 2001-2002 report NPCB, DGHS, MOHFW and GOI. . . [Google Scholar]
- Johnson CA, Cioffi GA, Liebmann JR, Sample PA, Zangwill LM, Weinreb RN. The Relationship Between Structural and Functional Alterations in Glaucoma: A Review. Semin Ophthalmol. 2000;15(4):221-3. [Google Scholar]
- Artes PH, Chauhan BC. Longitudinal changes in the visual field and optic disc in glaucoma. Prog Retin Eye Res. 2005;24(3):333-54. [Google Scholar]
- Strouthidis NG, Scott A, Peter NM, Garway-Heath DF. Optic disc and visual field progression in ocular hypertensive subjects: detection rates, specificity, and agreement. . Invest Ophthalmol Vis Sci. 2006;47(7):2904-10. [Google Scholar]
- Kass MA, Heuer DK, Higginbotham EJ. The Ocular Hypertension Treatment Study: a randomized trial determines that topical ocular hypotensive medication delays or prevents the onset of primary open-angle glaucoma. Arch Ophthalmol. 2002;120(6):701-13. [Google Scholar]
- Parrish RK, Schiffman JC, Feuer WJ, Anderson DR, Budenz DL, Wells-Albornoz MC. Ocular Hypertension Treatment Study Group. Test-retest reproducibility of optic disk deterioration detected from stereophotographs by masked graders. Am J Ophthalmol. 2005;140(4):762-4. [Google Scholar]
- Azuara-Blanco A, Katz LJ, Spaeth GL, Vernon SA, Spencer F, Lanzl IM. Clinical agreement among glaucoma experts in the detection of glaucomatous changes of the optic disk using simultaneous stereoscopic photographs. Am J Ophthalmol. 2003;136(5):949-50. [Google Scholar]
- Emery JM, Landis D, Paton D, Boniuk M, Craig JM. The lamina cribrosa in normal and glaucomatous human eyes. Trans Am Acad Ophthalmol Otolaryngol. 1974;78:290-7. [Google Scholar]
- Quigley HA, Addicks EM, Green WR, Maumenee AE. Optic nerve damage in human glaucoma. II. The site of injury and susceptibility to damage. Arch Ophthalmol. 1981;99:635-49. [Google Scholar]
- Yildirim E, Bilge AH, Ilker S. Improvement of visual field following trabeculectomy for open angle glaucoma. Eye. 1990;4(1):103-6. [Google Scholar]
- Kotecha A. Optic disc changes following trabeculectomy: longitudinal and localisation of change. Br J Ophthalmol. 2001;85(8):956-61. [Google Scholar]
- Aydin A, Wollstein G, Price LL, Fujimoto JG, Schuman JS. Optical coherence tomography assessment of retinal nerve fiber layer thickness changes after glaucoma surgery. Ophthalmol. 2003;110(8):1506-11. [Google Scholar]
- Raghu N, Pandav SS, Kaushik S, Ichhpujani P, Gupta A. Effect of trabeculectomy on RNFL thickness and optic disc parameters using optical coherence tomography. Eye. 2012;26(8):1131-7. [Google Scholar]
- Kotecha A, Spratt A, Bunce C, Garway-Heath DF, Khaw PT, Viswanathan A. Optic disc and visual field changes after trabeculectomy. Invest Ophthalmol Visual Sci. 2009;50(10):4693-9. [Google Scholar]
How to Cite This Article
Vancouver
Sarkar KC, Sarkar P, Bhattacharyya S. Optical coherence tomographic assessment of disc changes and automated perimetric assessment of visual field changes after glaucoma filtration surgery [Internet]. Indian J Clin Exp Ophthalmol. 2020 [cited 2025 Oct 01];6(2):185-188. Available from: https://doi.org/10.18231/j.ijceo.2020.040
APA
Sarkar, K. C., Sarkar, P., Bhattacharyya, S. (2020). Optical coherence tomographic assessment of disc changes and automated perimetric assessment of visual field changes after glaucoma filtration surgery. Indian J Clin Exp Ophthalmol, 6(2), 185-188. https://doi.org/10.18231/j.ijceo.2020.040
MLA
Sarkar, Kumaresh Chandra, Sarkar, Piyali, Bhattacharyya, Shashwat. "Optical coherence tomographic assessment of disc changes and automated perimetric assessment of visual field changes after glaucoma filtration surgery." Indian J Clin Exp Ophthalmol, vol. 6, no. 2, 2020, pp. 185-188. https://doi.org/10.18231/j.ijceo.2020.040
Chicago
Sarkar, K. C., Sarkar, P., Bhattacharyya, S.. "Optical coherence tomographic assessment of disc changes and automated perimetric assessment of visual field changes after glaucoma filtration surgery." Indian J Clin Exp Ophthalmol 6, no. 2 (2020): 185-188. https://doi.org/10.18231/j.ijceo.2020.040