|Year : 2014 | Volume
| Issue : 3 | Page : 102-107
Macular spectral domain optical coherence tomography data in Indian subjects with cataract
Vishal Katiyar, Shivani Sinha, Sanjiv Kumar Gupta, Siddharth Agrawal, Poonam Kishore, Vinita Singh
Department of Ophthalmology, King George‘s Medical University, Lucknow, Uttar Pradesh, India
|Date of Web Publication||7-Sep-2015|
Dr. Vishal Katiyar
Department of Ophthalmology, King George's Medical University, Lucknow - 226 003, Uttar Pradesh
Source of Support: Nil, Conflict of Interest: None declared.
Introduction: The objective of this study is to provide baseline optical coherence tomography (OCT) macular parameters data in Indian subjects with cataract and to compare these parameters with the published normative data on Indian population to understand the effect of cataract on macular thickness using cirrus spectral domain OCT. Material and Methods: This was a prospective, observational, cross-sectional analysis of 108 eyes of 108 cataract cases of north Indian origin. Results: It was observed that age of the patients and the best corrected visual acuity (BCVA) are not found to be the independent factor predicting the change in the mean values of different OCT parameters of macular thickness studied (linear regression analysis β = −2.197 to 0.34, P = 0.902–0.073). Comparison of mean values of different OCT parameters of macular thickness of studied patients with the normative population data from Indian population showed statistical difference in the values with noncataractous population having higher values for most of the studied parameters (t-test; t = 93.6–9.2, P = 0.007–0.043). Conclusion: Though the mean macular thickness of a cataract patient is lesser than that of population, age of the cataract patient does not independently predict the variation in baseline macular thickness. The BCVA achieved after an uneventful cataract surgery is found to be independent of baseline macular thickness of the patient. Moreover the presence of cataract or its grade is not associated with baseline macular thickness of the patient.
Keywords: Cataract, Indian, macular, optical coherence tomography, spectral domain
|How to cite this article:|
Katiyar V, Sinha S, Gupta SK, Agrawal S, Kishore P, Singh V. Macular spectral domain optical coherence tomography data in Indian subjects with cataract. Egypt Retina J 2014;2:102-7
|How to cite this URL:|
Katiyar V, Sinha S, Gupta SK, Agrawal S, Kishore P, Singh V. Macular spectral domain optical coherence tomography data in Indian subjects with cataract. Egypt Retina J [serial online] 2014 [cited 2020 Mar 30];2:102-7. Available from: http://www.egyptretinaj.com/text.asp?2014/2/3/102/164633
| Introduction|| |
Spectral domain optical coherence tomography (OCT) is a noninvasive test that can provide precise measurements of macular anatomy in vivo. A quantified value allows comparison of numerical data in the natural course of a disease or response to therapy. Cirrus spectral domain OCT (SD-OCT) provides definition, contrast and thickness of the retinal layers along with the volume of the retina, enabling to follow the progression of edema or atrophy more precisely. This is important for following the progression of edema or a serous detachment, either the natural history or after laser or surgical intervention., Studies report that the macular thickness vary not only between different ethnic groups, but also affected by demographic parameters like age and sex and its values have significant impact on the clinical decision making in various macular pathologies.
Presence of media opacities like cataract not only give rise to artifacts in OCT measurements, but also a significant decrease in observed values.,, Cataract is a commonly performed surgery, transient and clinically insignificant changes in the macular thickness have been observed with OCT, even after an uneventful cataract surgery., Cystoid macular edema is reported around 3% of uneventful cataract surgeries and about 6–21% of cases with vitreous loss during cataract surgery., To the best of our knowledge, baseline macular parameters data on cirrus SD-OCT and its variations associated with demographic and ocular variables in Indian subjects with cataract are not available. In Indian subjects with cataract, this data would help an ophthalmic surgeon in making informed clinical decisions, in the management of macular abnormalities, noticed before and after the cataract surgery. The objective of this study is to provide baseline OCT macular parameters data in Indian subjects with cataract and to compare these parameters with the published normative data on Indian population to understand the effect of cataract on macular thickness using cirrus SD-OCT.
| Material and Methods|| |
This was a prospective, observational, cross-sectional analysis of 108 eyes of 108 cataract cases of north Indian origin. All methods adhered to the tenets of the Declaration of Helsinki for research involving human subjects. Written informed consent was taken and the study protocol was approved by the Ethical Committee of the Institute. All patients above 35 years of age undergoing cataract surgery for visually significant cataract (senile cataract grading NS I-III) (phaco-emulsification with posterior chamber intraocular lens implantation) in the department of ophthalmology at a Medical University hospital were included. Exclusion criteria included, recent intraocular surgery, any systemic illness, which may affect the macular thickness, systemic medications, which may affect macular thickness and any preexisting macular disease.
All participants underwent a comprehensive ophthalmic examination, including review of medical history, visual acuity testing, slit lamp biomicroscopy, intraocular pressure (IOP) measurement by Goldmann applanation tonometry and dilated funduscopic examination. SD-OCT examination was performed with the cirrus high-definition-OCT models 5000. All subjects had the macular scans performed on the 1st day after surgery.
Optical coherence tomography protocol
512 × 128 scans from top to bottom protocol was used for retinal thickness assessment. The software then constructs a retinal map by aligning the scans. In addition to creating a retinal thickness map, the SD-OCT software calculates the retinal volume for each map., Each scan was individually reviewed, and segmentation lines were adjusted to ensure the accuracy in macular thickness measurements. Macular thickness was reported in a modified Early Treatment of Diabetic Retinopathy Study macular map with the central sub-field 1 mm in diameter and the inner and outer subfields having diameters of 3 mm and 6 mm, respectively [Figure 1]a,[Figure 1]b,[Figure 1]c. The retinal thickness in the inner and outer subfields, the central foveal thickness (CFT), the center point thickness (CPT), and the macular volume were calculated. CPT was defined as the average of six radial scans centered at the foveola, whereas the CFT was defined as the average of all points within the central 1 mm diameter circle surrounding fixation [Figure 2].
|Figure 1: (a-c) Macular thickness map using Early Treatment of Diabetic Retinopathy Study circles of 1 mm, 3 mm, and 6 mm showing the mean thickness in each of the nine subfields|
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|Figure 2: The standard Early Treatment of Diabetic Retinopathy Study subfields dividing the macula into central fovea, inner macula, and outer macula. CFT: Central foveal thickness, SIM: Superior inner macula, NIM: Nasal inner macula, IIM: Inferior inner macula, TIM: Temporal inner macula, SOM: Superior outer macula, NOM: Nasal outer macula, IOM: Inferior outer macula, TOM: Temporal outer macula|
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The macular parameters were compared with the published normative data on the healthy Indian population. Descriptive statistics included mean ± standard deviation for the normally distributed variables. Linear regression analyzes were done to assess the effects of age and final visual acuity on macular parameters measured by SD-OCT. Student's t-test was used to compare the effects of gender on the macular thickness and to assess the difference in the observed data in study group and the normative population data from Indian population. Statistical analyzes were performed with commercial software (IBM SPSS 20.0 statistics, USA).
| Results|| |
The prospective data of the study patients was collected. All eyes had an IOP of 21 mmHg or less with no history of increased IOP and had normal ocular examination results. Study patients have a mean age of 58.5 ± 9.5 years, with male: female ratio of 7:4. Patients have mean best corrected visual acuity (BCVA) of 0.201 ± 0.17 logMAR, with average spherical refractive error of −0.80 ± 0.39 D and average cylinder error of −0.78 ± 0.40 D. Most of the patients had nuclear Grade 2–3 (84%), cortical Grade 2–3 (79%) and posterior sub-capsular Grade 1–2 (80%) cataract as shown in [Table 1].
Gender and macular thickness
We did not find any statistical difference in the mean age and BCVA between male and female patients. There was no statistical difference in the mean values of different OCT parameters of macular thickness between male and female (the t-test; t = −0.510 to 0.898, P = 0.373–0.978) as shown in [Table 2] and [Figure 3]a,[Figure 3]b.
|Figure 3: (a and b) Scatter diagram of dependent variable age and best corrected visual acuity|
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Cataract and macular thickness
The patient were divided in four groups depending on the grades of cataract for each type (cortical, nuclear and posterior sub-capsular cataract) and the difference in the mean thickness is assessed with Kuskal–Wallis H test. There is no statistical difference in the mean values of different OCT parameters of macular thickness in the four grades of cataract in any of the cataract type (cortical, P = 0.195–0.997; nuclear, P = 0.216–0.973 and posterior sub-capsular cataract, P = 0.54–0.961).
Regression analysis was done to assess if age and the BCVA attained after cataract surgery, independently affect the values macular thickness parameters recorded in the patients. The age of the patient and the BCVA were not found to be the factor predicting the change in the mean values of different OCT parameters of macular thickness studied as shown in the [Table 3] (linear regression analysis β = −2.197 to 0.34, P = 0.902 − 0.073).
Cataractous and noncataractous patients
Comparison of mean values of different OCT parameters of macular thickness of studied patients with the data of the studied population and normative population data from Indian population (Appukuttan et al. 2014) using Welch alternate test showed statistical difference in the values with noncataractous population having higher values for most of the studied parameters (t-test; t = 93.6–9.2, P = 0.007–0.043) as shown in [Table 4].
|Table 4: Difference in the mean of OCT parameter of cataract patients in comparison with normal population|
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| Discussion|| |
To the best of our knowledge, studies on the normative data in cataract patients have not been published. In the present study, we assessed macular thicknesses on the 1st postoperative day after uncomplicated cataract phaco-emulsification to generate normative data macular thickness on Cirrus OCT in Indian cataract patients. We observed that the mean central average thickness in studied male patients were 243.4 ± 18.3 μm and in studied females were 239.1 ± 16.2 μm. Using the criteria of mean ± 2 SD, which include 95% of the population, we suggest that 205–275 μm may be taken as the normal macular thickness for both males and females in Indian cataract patients which definitely lower that the normal range of macular thickness in healthy Indian population as recommended by Appukutan et al. (220–300 μm). The lesser macular thickness observed in cataract patients was expected because of higher age when compared to the mean age of the population from which normative data was drawn (Appukuttan et al. 2014).
We did not observed the age of the cataractous patient to be an independent factor predicting the changes in the macular thickness as observed on OCT. The studies by Grover et al. and Huang et al. using spectralis, observed a similar lack of a statistical association between macular thickness and age. Again the study by Appukuttan et al., on healthy Indian population observed that the increasing age as an independent factor predicting the decline in the macular thickness. This disparity may partly be due to the difference in the age distribution of cases in the two studies. In our study, the patients were having the mean age of 58.5 years (range 35–85 years) where as in Appukuttan et al. study, the study population has the mean age of 35.5 years (range 20–60).
We did not observe any difference in the CFT of any other OCT parameter for macular thickness between men and women (P =0.373–0.978). This observation is similar to what has been reported by Tewari et al. and Grover et al. But normative data on macular thickness of Indian population by Appukuttan et al. and studies by Song et al., Wong et al., and Massin et al. found that males to have significantly higher average retinal thickness as compared to females. However, the difference could be attributed to the fact that none of the above studies have been done on the cataractous patients.
Studies have reported subclinical increase,,,, or decrease, macular thicknesses on the 1st day after uncomplicated cataract surgery. It is presumed that retinal thickness does not vary due to surgery-induced inflammation shortly after cataract extraction. Therefore, the significant decrease observed in some studies,, could be related to the influence of lens opacity on the preoperative OCT measurements or to an apparent thinning of the retina when the lens is replaced by an IOL. Indeed, cataract may cause light-scattering effect that may give rise to artifacts in OCT measurements. Thus, the 1st postoperative day measurements might reflect the true "baseline" retinal thickness.
We did not observe the baseline macular thickness of the cataractous patient to be independent factors predicting the final visual outcome of the patient. A similar observation is made by Giansanti et al. and Gharbiya et al. A correlation between visual acuity and postoperative macular thickness has been found in two previous reports but these studies did not assess whether the 1st day macular thickness is an independent factor predicting the final visual outcome of the patient.,
In comparison to normative data of Indian population, cataractous cases in our study were found to have statistically significant lesser macular thickness. It is unclear whether this difference between the cataractous and normal population could be attributed to the presence of cataract in these patients. There was no difference in the OCT protocol, instrument or the accepted signal strength of the OCT scan in the present study and the Appukuttan et al. study from which the normative data was drawn. In our study, grade of nuclear, cortical or posterior sub-capsular cataract categories are not associated with any differences in the mean macular thickness in the study patients. There are no studies on the effect of cataract on the baseline macular thickness. In the Kim et al. study, patients with unilateral cataract have not reported any difference in macular thickness between cataractous and noncataractous eye. But, the study was done on cases of pediatric cataract with a mean age of 7.5 years.
We concluded that though the mean macular thickness of a cataract patient is lesser than that of the population, age of the cataract patient does not independently predict the variation in baseline macular thickness. The BCVA achieved after an uneventful cataract surgery is found to be independent of baseline macular thickness of the patient. Moreover, the presence of cataract or its grade is not associated with baseline macular thickness of the patient.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4]