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| ORIGINAL ARTICLE |
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| Year : 2018 | Volume
: 26
| Issue : 2 | Page : 121-127 |
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The relationship between vertical cup–disc ratio and body mass index in a population of adult Saudi females
Fahad Al Wadani, Kaberi B.K Feroze, Reem Al Yahya
College of Medicine, King Faisal University, Al Hasa, Saudi Arabia
| Date of Web Publication | 13-Feb-2019 |
Correspondence Address:
Dr. Fahad Al Wadani
College of Medicine, King Faisal University, Al Hasa
Saudi Arabia
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/njo.njo_6_18
Purpose: The vertical cup–disc (C/D) ratio is useful clinically in optic-disc assessment in glaucoma suspects and diagnosing glaucomas and is thought to also be influenced by many ocular and systemic factors. The body mass index (BMI) is said to be an important parameter which influences vertical C/D ratio and different studies have shown different correlation between these two variables. The aim of the study was to assess the relationship of vertical C/D ratio with BMI in a population of Saudi adult females. Methods: One hundred and one female participants in the age group 18 to 40 years were included in a cross-sectional study after obtaining information regarding demographic data, ocular/systemic diseases, and surgeries by an oral interview. The BMI was calculated as ratio of body weight divided by the square of the body height. C/D ratio was recorded with direct ophthalmoscopic examination and examination with 90-D (Volk) lens. Analysis of variance was used to examine the BMI on vertical C/D ratio. A P-value <0.05 was considered to be statistically significant with confidence interval of 95%. Results: The mean BMI was 22.7 (±4.49) and the mean C/D ratio was 0.22 (±0.14). No significant relationship between increasing vertical C/D ratio and BMI P-value 0.154 was found. Conclusion: This study, conducted as a pilot study to investigate the relationship between C/D ratio and BMI in a young female Saudi population, found no significant relationship between vertical C/D ratio and BMI. This relationship is important as it helps to rule out effect of BMI on C/D ratio parameters in this population.
Keywords: Body mass index, glaucoma suspect, vertical cup–disc ratio
How to cite this article:
Al Wadani F, Feroze KB, Al Yahya R. The relationship between vertical cup–disc ratio and body mass index in a population of adult Saudi females. Niger J Ophthalmol 2018;26:121-7 |
| Introduction | |  |
Optic-disc examination is a vital tool that gives clues to many ocular and systemic diseases. Different optic-nerve pathologies affect the appearance of the optic-nerve head.[1],[2] Optic-disc cupping greater than 0.7 usually points to the presence of glaucoma.[3] The cup–disc (C/D) ratio is useful clinically in optic-disc assessment in glaucoma suspects,[4] childhood glaucomas,[5] and glaucoma progression.[6] High myopia is another condition which demonstrates optic-disc changes.[7],[8],[9],[10],[11] C/D ratio assessment is also of concern to the neuro-ophthalmologists, in conditions such as congenital and acquired optic neuropathies,[12] raised intracranial pressure,[13] and also in nonarteritic ischemic optic neuropathy.[14] Diabetic patients with poor metabolic control, severe retinopathy, and those who have received laser treatments are prone to develop retinal nerve fiber layer atrophy and optic-disc changes.[15] Thus, evaluation of optic disc is of utmost importance in so many ocular conditions, especially glaucomas. Vertical C/D ratio is considered one of the best parameters to discriminate between healthy and glaucomatous eyes[2] and predicting future development of Glaucoma.[16],[17],[18],[19],[20],[21],[22],[23] Different population-based studies have found that vertical C/D ratio ranges from 0.43 to 0.56,[24],[25],[26],[27] whereas many other studies have mentioned an average vertical C/D ratio around or less than 0.3 in normal participants.[28],[29],[30],[31],[32]
The vertical C/D ratio is influenced by many ocular and systemic factors including race,[1],[25],[28] genetic factors,[33] birth weight,[34] age,[18],[32],[35],[36], sex,[37] longer axial lengths,[38] and IOP (intraocular pressure) and disc area.[39],[40],[41] The body mass index (BMI) is thought to be an important parameter which influences vertical C/D ratio. Some studies have found a positive correlation between vertical C/D ratio and BMI,[40],[42] whereas many studies have found an association between lower BMI and vertical C/D ratio[28],[37],[43],[44],[45] and some were statistically insignificant.[46]
The BMI, given in units kg/m2, has the dimension of an area density, the average value of which, for normal, healthy participants, has so far been recommended as 21.7.[47] Higher BMI was found to be a risk factor for posterior subcapsular lens opacities,[48] age-related macular degeneration,[49] increased retinal venular diameter,[50] IOP,[51] and hyperopic refraction.[52]
This study attempts to assess the relationship of vertical C/D ratio with the height, weight, and BMI in a population of Saudi adult females. The age group of 18 to 40 years was selected in this study, because it is considered to be less than the average age group of glaucomas[53],[54],[55],[56] and could allow better analysis of factors affecting C/D ratio prior to initiation of glaucomatous damage. We selected a female population as some studies have shown a higher prevalence of glaucomas in females in Saudi Arabia,[56],[57] with the intention of conducting a further study involving all populations.
| Methods | | |
This cross-sectional study was conducted in the College of Medicine and the University Health Centre, King Faisal University, Al Hasa, after getting the approval of the concerned authorities. Informed verbal consent was obtained from all participants. A convenience sample of 101 females was selected.
The study population was females in the age group 18 to 40 years. Both eyes were included in the study.
Inclusion criteria:- Saudi females, age 18 to 40 years
- No history of systemic diseases
- No history of significant ocular diseases or ocular surgeries
- Visual acuity better than or equal to 6/9
- Refraction within ±0.5D
- IOP < 21 mmHg
Details such as age, occupation, history of systemic/ocular diseases, and history of surgeries/injuries were obtained by an oral interview with the candidates. The BMI was calculated as ratio of body weight (measured in kilograms) divided by the square of the body height (measured in meters). The BMI was classified as underweight (<18.5), normal (18.5–25), overweight (25–30), and obese (>30).
The visual acuity was recorded with a Snellen’s chart, and a streak retinoscope was used to rule out refractive errors greater than ±0.5. Slit lamp examination was used to rule out any anterior segment pathologies. Goldmann applanation tonometry was performed to check the IOP. The vertical C/D ratio was recorded with a direct ophthalmoscopic examination (Welch Allyn ophthalmoscope using the 5° aperture) and confirmed by examination with 90-D (Volk) lens (Volk Optical Inc., OH). The same was performed by two ophthalmologists, and the average value was taken. Patients with small pupils were assessed after pupillary dilatation with tropicamide drops. The vertical CDR was taken as the longest vertical cup diameter divided by the longest vertical disc diameter. The contour of the cup was considered as the margin of the cup. Slit lamp measurement of the CDR was taken, and the two ophthalmologist had previously worked together on glaucoma patients, helping to standardize their estimations of CDR. The same was performed by two ophthalmologists, who have worked together previously in the glaucoma unit, and the average value was taken.
Statistical analysis
SPSS (Statistical Package for the Social Sciences) 21 (IBM Corporation) for Mac was used to analyze the data. Descriptive statistics and frequencies of the data were measured. Factorial analysis of variance (ANOVA) was used to examine the BMI in relation to vertical C/D ratio. A P-value <0.05 was considered statistically significant with confidence interval of 95%.
| Results | | |
Young adult female participants in the age group 18 to 40 years were included in the study. There were 101 participants included in the study. A total of 202 eyes were included in the study. The mean age of the study population was 21.8 ± 3.6 years [Figure 1].
The BMI in this study ranged from 15.2 to 44.9, with a mean BMI of 22.66 ± 4.49. A total of 72.3% of the participants were in the normal BMI range [Figure 2].
On comparing the age group of the participants with the BMI, it was noted that with increasing age, there was a tendency to develop a higher BMI [Figure 3].
Most of the participants had C/D ratios less than 0.5. C/D ratios ranged from no cup to 0.7. The mean C/D ratio in this study was found to be 0.219 ± 0.14 [Table 1].
Analysis of the BMI and C/D ratio was performed using ANOVA. Analysis of the data showed that the P-value was 0.154, which showed that there was no association between BMI and C/D ratio [Figure 4]. In addition, it was noted that there was no association between different BMI categories and C/D ratio.
| Discussion | | |
The C/D ratio is one of the most important parameters in diagnosis and follow-up of glaucomas and is said to be influenced by many factors, which could lead to misinterpretation of glaucoma diagnosis. BMI has, long, been considered to be one of the important factors influencing C/D ratio.[28],[37],[40],[42],[43],[44],[45],[46] This study was conducted to find out the relationship between vertical C/D ratio and BMI in a population of young Saudi adults. This is probably the first time a study of this kind was conducted in this area of Saudi Arabia [Table 2].
The mean age of participants in our study was 21.8 ± 3.6 years. Other studies analyzing this relationship have a mean age of 35 ± 13.29 years,[46] with a much higher average age in other studies.[25],[26],[28],[38]
The mean BMI in our study was 22.66 ± 4.49, which was in the normal range. Most other studies also show majority of participants having normal BMI.[38],[46]
The mean vertical C/D ratio in our study was found to be 0.219 ± 0.14. Other studies show a mean C/D ratio of 0.38 ± 0.13,[46] 0.49 ± 0.14,[25] 0.48,[26] 0.34 ± 0.12,[28] 0.44 ± 0.17.[38]
The Nigerian Port Harcourt study found a positive correlation between overweight BMI ranges and larger C/D ratios.[46] Higher BMI was found to be associated with larger vertical disc diameter.[38] Other studies have reported an association between lower BMI and larger C/D ratios.[28],[37],[42]
This study was conducted as a pilot study to investigate the relationship between C/D ratio and BMI in a young female Saudi population. There was found to be no significant relationship between increasing vertical C/D ratio and BMI. This relationship is very important as it helps to rule out effect of BMI on C/D ratio parameters. This is the first time that this kind of study has been conducted in this area. So, the inferences of this study are thought to be important in optic-disc analysis for glaucoma diagnosis. The limitations of this study were thought to be the small sample size. Further studies are required in all age groups of both sexes to confirm a similar association, which would go a long way in helping glaucoma specialists to assess patient status, follow-up, and diagnose borderline cases.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2]
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