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 Table of Contents    
ORIGINAL ARTICLE
Year : 2022  |  Volume : 15  |  Issue : 3  |  Page : 295-298  

Pattern of astigmatism using partial coherence interferometry in patients of different age groups undergoing cataract surgery


1 Department of Ophthalmology, Armed Forces Clinic, New Delhi, India
2 Department of Ophthalmology, Armed Forces Medical College, Pune, Maharashtra, India
3 Department of Ophthalmology, Base Hospital, New Delhi, India
4 Department of Ophthalmology, Command Hospital, Pune, Maharashtra, India
5 Department of Ophthalmology, Armed Hospital R and R, New Delhi, India

Date of Submission24-Nov-2021
Date of Decision22-Dec-2021
Date of Acceptance14-Mar-2022
Date of Web Publication02-Nov-2022

Correspondence Address:
Mohini Agrawal
Department of Ophthalmology, Command Hospital, Pune, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ojo.ojo_345_21

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   Abstract 


BACKGROUND: Astigmatism is a refractive error that accounts for 70% of refractive errors in the elderly population. It is important to be aware of the distribution, extent, and type of astigmatism in patients undergoing cataract surgery to guide in reducing postoperative spectacle dependency.
AIM: To study the demography, amount, and pattern of astigmatism using partial coherence interferometry in patients of different age groups undergoing cataract surgery.
MATERIALS AND METHODS: A cross-sectional observational study. Keratometry and demography data were collected for patients planned for cataract surgery at a tertiary care center between January 2018 and December 2019. It was done with noncontact partial coherence interferometry in patients above 50 years undergoing cataract surgery.
RESULTS: Out of 385 patients, 216 (56%) were males and 169 (44%) were females. Astigmatism was more common in males than females (P = 0.00). Against-the-rule (ATR) astigmatism was found in 262 cases (68%), while with-the-rule (WTR) astigmatism was seen in 87 cases (23%). ATR was more common than WTR (P = 0.00). The number of patients with ATR seems to be increased with aging eyes and was more common between 61 and 70 years of age group (P = 0.00). The total amount of astigmatism increased with increasing age (P = 0.00029) which was found to be significant. Frthermore, there was a gradual change of WTR to ATR astigmatism with aging eyes.
CONCLUSION: Two hundred and sixty-two cases (68%) had ATR astigmatism mainly seen in the age group of 61–70 years. Majority had astigmatism up to 1.0 D that can be easily managed by simple cost-effective keratorefractive procedures like on-axis incision, opposite clear corneal incision, and limbal relaxing incisions.

Keywords: Against-the-rule, astigmatism, cost-effective, pattern, with-the-rule


How to cite this article:
Vats S, Kumari L, Goenka R, Agrawal M, Mishra S. Pattern of astigmatism using partial coherence interferometry in patients of different age groups undergoing cataract surgery. Oman J Ophthalmol 2022;15:295-8

How to cite this URL:
Vats S, Kumari L, Goenka R, Agrawal M, Mishra S. Pattern of astigmatism using partial coherence interferometry in patients of different age groups undergoing cataract surgery. Oman J Ophthalmol [serial online] 2022 [cited 2022 Dec 4];15:295-8. Available from: https://www.ojoonline.org/text.asp?2022/15/3/295/360417




   Introduction Top


With rampant advances in science and technology, quick and easy internet access, social networking, and literacy levels of the present world, the modern generation's anticipation for a better lifestyle including vision are sky-rocketing, be it postcataract surgery. To encounter the needs and content of the patients, an accurate preoperative assessment of patients, expertise intraoperative techniques, and proper intraocular lens (IOL) implantation are of utmost importance nowadays, to have good surgical outcomes. Cataract surgery should not only address lens extraction and IOL implantation but also concentrate in correcting spherical and astigmatism components of refractive errors at the same setting by choosing apt techniques of surgery like site of incision, use of femto-laser-assisted keratotomy and choosing Toric IOL for correcting preoperative astigmatism. Astigmatism is a refractive error that accounts for 70% of refractive errors in the elderly population. The prevalence of preexisting corneal astigmatism of >1.00 diopter (D), >1.5 D and >2.00 D has been reported to range from 32.5% to 45.5%, 21.0% to 26.20% and 8% respectively in patients with cataract.[1],[2],[3] The measurement of corneal astigmatism by manual or automated keratometer may cause compromised readings and postoperative visual outcomes as they work on assumptions. Optical low coherence reflectometry (OLCR) permits certain measurement of ocular biometric values and have been proven more accurate than conventional techniques.[4] The prevalence of astigmatism in the elderly population undergoing cataracts is increasing globally and has been reported by various studies conducted in the United States, China, European countries, and Thailand.[5],[6],[7],[8],[9],[10],[11]

However, there are only a few reports in the Indian population. This study aims to assess the demographics and distribution of corneal astigmatism by OLCR in the participants undertaking cataract surgery. The study also aims to evaluate the extent and type of astigmatism in these patients which might help in curtailing postoperative spectacle dependency.


   Materials and Methods Top


In this study, patients' data were collected between January 2018 and December 2019 in the outpatient department of ophthalmology of a tertiary care hospital. It was approved by Institutional Ethics Committee and has been conducted in accordance with the “Declaration of Helsinki.” A written informed consent was taken from all the study subjects. The data were reviewed and analyzed. Patients above 50 years having astigmatism. Optical biometry and demographic records were screened for all patients who had undergone phacoemulsification in the department. Patients with use of contact lens, corneal disease, corneal inflammation or trauma or corneal surgery, dry eye, younger than 50 years and a dense cataract that did not allow IOL Master measurements were excluded from the study. Routine eye examinations were performed on all patients including visual acuity, refraction, tonometry, slit-lamp evaluation, dilated fundus examination, and IOL master measurements. IOL master analyses six-light reflections projected onto the anterior corneal surface within 2.3 mm radius and can be used as an automated keratometry. Reports show that IOL master measures corneal astigmatism accurately. Experienced technicians collected the keratometric data for consecutive patients using IOL master and mean of six readings was used for the study. Corneal astigmatism was categorized as with the rule (WTR) when steeper meridian lies between 60° and 120°, against the rule (ATR) when the steeper meridian lies between 0°–30° and 150–180° and, oblique, when it is not ATR/WTR.

Data was analyzed using SPSS for Windows (version 20.0 software SPSS 20.0 IBM, Pune, India). Qualitative data variables were expressed as frequency and percentage while quantitative data variables expressed as Mean, standard deviation and Median Chi-square test was used to calculate the relationship between age and type of astigmatism (ATR, WTR), and the distribution of astigmatism in relation to age and gender. Spearman's correlation rank test was used to assess the correlation between the amount of astigmatism and age. A P < 0.05 was taken as statistically significant.


   Results Top


A total of 385 patients were included in this study. The demographic profile of the studied population is depicted in [Table 1]. Out of 385 patients, majority (56%) were males. [Table 2] represents the pattern of astigmatism in males and females. [Table 3] represents the pattern of astigmatism in different age groups, respectively. The distribution of the amount of astigmatism for the different age groups is depicted in [Table 4] and in [Figure 1]. On relating the type of astigmatism with age, it was found that with progressing age, there was a propensity for an increase in ATR astigmatism and a decrease in WTR astigmatism.
Figure 1: Distribution of amount of astigmatism in diopters in various age-groups

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Table 1: Gender-age wise distribution of patients

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Table 2: Gender-wise distribution of various pattern of astigmatism

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Table 3: Distribution of pattern of astigmatism in various age-groups

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Table 4: Amount of astigmatism in diopters in various age-groups

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   Discussion Top


The presence of astigmatism greatly influences visual outcomes after cataract surgery. Thus, it is important to address corneal astigmatism during surgery to provide spectacle independence to the patients. Several studies have investigated the prevalence of corneal astigmatism using IOL Master, which measures corneal parameters as well as enables easy and reliable calculation of IOLs.[5],[6],[7],[8],[9],[10] This study revealed the distribution of all 385 candidates in a single hospital. The IOL Master database was accessed for all patients in 24 months. In terms of gender distribution, our study showed that the number of male patients (56%) was greater than that of females (44%) which was found to be in accord with many studies,[12],[13] except a few which showed opposite results.[8],[10],[14] In terms of the pattern of astigmatism, ATR was more common comprising 68% cases and increasing with aging eyes; while WTR astigmatism was seen decreasing with age which was in consistent with previous studies.[15],[16]

The change of astigmatism was significant as the age advanced (P < 0.05) and found to be more between 61 and 70 years of age-group. There was a steady shift from WTR-to-ATR astigmatism with an increase in age. This change was seen primarily after 40 years of age; however, the same was not seen with oblique astigmatism. Comparable outcomes have been reported in previous studies.[17] Numerous factors such as physiological changes in corneal curvature with age, pressure from eyelids, intraocular pressure, and pressure of extraocular muscles might be responsible factors for the shift of ATR and WTR with age.

Cataract is one of the most common causes of the visual problem in elderly patients. So, it is important to accurately measure the power and type of astigmatism before taking-up patients for cataract surgery. The type of incision, site of incision, and plan for the type of IOL implantation largely affect the outcomes of surgery. By improving biometric devices and IOL power calculations, postoperative refractive correction can be reduced to ± 0.5 D of the targeted spherical correction.[18],[19],[20] Therefore, residual astigmatism becomes a significant postoperative factor influencing the outcome of vision. Several techniques exist to correct corneal astigmatism during cataract surgery including limbal relaxing incisions, opposite clear corneal incision, excimer laser refractive procedures, femtosecond laser-assisted astigmatic keratotomy, laser in situ keratomileusis, and toric IOL implantation.[8],[10],[14],[21] The procedure chosen primarily depends on the precise measurements of preoperative corneal astigmatism. A greater number of surgeons are using toric IOLs to correct astigmatism of more than 1.50 D in potential candidates. This is a very safe, stable, and efficacious technique reported.[22] Recent studies have shown that a greater number of people with astigmatism are going to increase.[23] With an increase in the number of the aging population and a higher demand for improved vision, the need for correction of astigmatism with toric IOLs or other methods will increase in the coming era.

There are many assets in this study. To the best of my knowledge, this is one of the very few Indian studies where astigmatism was calculated by using OLCR and underlines the fact that the probability of a patient demanding astigmatic correction increases with advancing age. Similarly, majority of the patients had astigmatism equal to <1.0 D which can be easily managed by low-cost keratorefractive procedures like on-axis incision, opposite clear corneal incision and limbal relaxing incisions to provide a cost-effective visual rehabilitation in a developing country like India. This indicates that only a small number of people will require toric IOLs and other refractive procedures in this population. However, the study is limited by a small sample size and further studies are warranted to support the same.


   Conclusion Top


This study revealed the prevalence of different patterns of astigmatism in patients more than 50 years of age undergoing cataract surgery and recorded up to 1.0 D of astigmatism in 67% of cases, which should be addressed during cataract surgery by cost-effective procedures. The amount of astigmatism increases with age, being more prevalent between 61 and 70 years of age-group. In view of an increase in the trend of ATR with aging eyes, corneal astigmatism should be resourcefully managed in the same setting of cataract surgery.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

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    Figures

  [Figure 1]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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