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Ocular Biometry, Keratometry Reading and Intra Ocular Pressure in age-related cataract patients with and without pseudoexfoliation Syndrome.

Byline: Ebrahim Shirzadeh, Arash Akaberi and Ma'ssoumeh Bemani Naeini

ABSTRACT

Objective: This study aims at making a comparison between Ocular Biometry, Keratometry Reading and Intra Ocular Pressure in age-related cataract patients with and without Pseudo Exfoliation Syndrome.

Methodology: A clinical-based cross-sectional study was carried out on 118 patients in 2008, with and without pseudoexfoliation syndrome who were candidates for age-related cataract surgery. Ocular Biometry, the related components including Anterior Chamber Depth, Lens Thickness, Vitreous Chamber Depth and Axial Length were measured using an A-scan ultrasound device. Corneal Power and Intra Ocular Pressure were also measured using keratometer and applanation tonometry, respectively.

Results: Of the 118 patient with mean age 68.97+-11.02 years old, 49% were men. Mean age was 71.08+-11.19 and 66. 91 +- 10.54 years for male and female respectively. 36.4% of total patients had PXS and among them 21.2% of male and 15.3% of the females had Pseudoexfoliation Syndrome. In Ocular Biometry components, the mean of Anterior Chamber Depth was shallower in the patients with Pseudoexfoliation Syndrome than those without it (P=0.049). Also mean Intra Ocular Lens power was greater in patients with Pseudoexfoliation Syndrome than those without it (p=0.046).

Conclusion: It seems that patients with age related-cataract along with Pseudoexfoliation Syndrome need larger Intra Ocular Lens power and have shallower Anterior Chamber Depth.

KEY WORDS: Ocular Biometry; Intra Ocular Pressure; Intra Ocular Lens; Cataract; Pseudoexfoliation Syndrome.

How to cite this article: Shirzadeh E, Akaberi A, Naini MB. Ocular Biometry, Keratometry Reading and Intra Ocular Pressure in age-related cataract patients with and without pseudoexfoliation Syndrome. Pak J Med Sci 2012;28(3):492-495

INTRODUCTION

The cataract is severe lens opacity or clouding of crystalline lens which brings about vision disorders. In its early stages, the disorder is termed lens opacity and the more severe vision-reducing stages are named cataract. Age-related cataract is predominantly a disease of middle and older age and it is the main and major cause of low vision and blindness in all countries of the world.1

Pseudoexfoliation syndrome (PXS) is a generalized disorder of the extracellular matrix and characterised by the production of abnormal basement membrane-like or protein-like material in several intraocular tissues including anterior lens capsule and extraocular tissues.2,3

Numerous studies were previously conducted on the relationship between stature4-6, refractive error7-10 birth size11, education and socioeconomic conditions12, age-related cataract (lens opacity)13,14 and axial ocular dimensions. However, more knowledge is needed about some related factors such as, ocular biometry, keratometry reading (KR) and intra ocular lens (IOL) measurements in patient with pseudoexfoliation syndrome (PXS).

Therefore, the aim of this study was to compare between Ocular Biometry data, Keratometry Reading (KR) and Intra Ocular Pressure (IOP) measurement in age related cataract patients with and Without PXS.

METHODOLOGY

Study Participants: A clinical-based cross-sectional study was carried out on 118 patients, aged 32 to 99 years old with and without pseudo exfoliation syndrome who were candidates for cataract surgery. The study was completed over a period of five months, from April to September, 2008. For the purpose of validity and reliability of the ocular findings, all the patients were examined by one single ophthalmologist in an eye clinic.

Visual Acuity test: First of all eye examinations such as distance Visual Acuity (VA) was done. Based on the VA (numeric notation measurements), the patients were classified into five groups: Light Perception (LP), Hand Motion (HM), Counting Finger (CF), 1/10 less than VA less than 3/10, and VA greater than 3/10.

Age-related cataract diagnostic: A slit lamp was used to grading the cataracts as clinically into five subgroups, including Nuclear Sclerosis (NS), Posterior Sub Capsular (PSC), Cortical Cataract (CC), Mixed Cataract (Mix C) and Mature Cataract (Mat C).

Pseudoexfoliation Syndrome diagnostic: The criterion for diagnosing PXS was the presence of pseudoexfoliation material in any of the anterior segment structures that can easily be detected by slit lamp examination.

Table-I: Distribution of cataract.

Cataract n(%)

posterior sub capsular cataract 15(12.7)

nuclear sclerosis 12(10.2)

cortical cataract 3(2.5)

mixed cataract 65(55.1)

mature cataract 23(19.5)

Total 118(100)

Keratometry Reading: Using Keratometer, HAAGSTREIT instrument (Jawal modle), KR was done by measuring the corneal curvature radius at two meridians, each 90deg apart. Also corneal astigmatism calculated as difference between both Keratometry principals' meridians.

Assessment of Ocular Biometry: Ocular dimensions including anterior chamber depth (ACD), lens thickness (LT), vitreous chamber depth (VCD), axial length (AL) and Intra ocular lens (IOL) were measured with an A-mode contact ultrasound (10MHz Nidek) device. Also SRK-T formula was used for IOL power calculation.

IOP measurements: The IOP of both eyes were recorded using Goldmann applanation tonometry (HAAG-STREIT, Swiss). Finally, funduscopy was performed with +78 D lens, when feasible.

Statistical Analysis: Continuous variables were expressed as mean +- standard deviation (SD).Chisquare test was used to assess the difference proportion of men and women with and without PXS. We used independent t-test to compare means of Keratometry at principle meridian one (K1), Keratometry at principle meridian two (K2), ACD, VCD, LT, AL, IOP and IOL in these patients. To compare Age, K1, K2, ACD, and AL in three categories of astigmatism one way analysis of variance was used. All statistical analyses were performed using SPSS version 11.5. A P-value less than 0.05 was considered to be statistically significant.

RESULTS

Data were available on 118 patients with phakic eyes with and without pseudo exfoliation syndrome who volunteered for age-related cataract surgery. PXS was found in 36.4% (43) of the eyes with 18.6% (22) cases affecting the right eye and 17.8% (21) cases in the left eye. In terms of sex, 21.2% (25) of the males and 15.3% (18) of the females had PXS. Chi square test revealed that the differences between sexes for PXS are not statically significant. The average age of 58(49%) males was calculated as 71.08 +-11.19 years.

Table-II: Distribution of visual acuity.

Visual acuity (VA) n(%)

Light perception 21(17.8)

Hand motion 5 (4.2)

Counting finger 78 (66.1)

1/10 less than VA less than 3/10 13 (11)

VA greater than 3/10 1(0.8)

Total 118(100)

Table-III: Ocular biometry, KR, IOP and IOL measurements in terms of PXS.

PXS Mean+-SD p-value

Keratometry at principle meridian one (D) Yes 44.96+-1.61 0.053

No 44.43+-1.30

Keratometry at principle meridian tow (D) Yes 44.22+-2.01 0.457

No 44.45+-1.32

Mean of keratometry at principle meridian one and tow (D) Yes 44.58+-1.68 0.505

No 44.41+-1.15

Anterior chamber depth (mm)

Yes 2.65+-0.32 0.049

No 2.79+-0.39

Length thickness (mm) Yes 4.08+-0.46 0.658

No 4.12+-0.52

Vitreous Chamber Depth (mm) Yes 15.97+-0.90 0.306

No 16.20+-1.26

Axial length (mm) Yes 22.70+-0.88 0.071

No 23.11+-0.90

Intra ocular pressure (mmHg) Yes 12.35+-2.38 0.678

No 12.18+-1.96

Intra ocular lens (D) Yes 21.74+-2.12 0.046

No 20.44+-3.89

As for 60 (51%) female subjects, the average age was 66.91 +- 10.54 years. Independent sample t-test revealed that there was a statistically significant difference in age between males and females (p=0.039). Forty nine percent of the examined eyes were right and the other fifty one percent were left eyes. Independent sample t-test revealed that there was no statistically significant difference between right and left eyes for ocular biometry parameters, IOP and IOL power (P greater than 0.05).

The distribution of VA and cataract subgroups is shown in Table-I and Table-II. The mean of Ocular biometry, KR, IOP and IOL measurements, in terms of PXS is summarized in Table-III. The means of age and IOL power were greater in the patients with cataract with PXS than those without PXS (p-value less than 0.001 and less than 0.046, respectively). Also, the mean of ACD was shallower in the patients with PXS than the other patients (p=0.049).

The results of one way ANOVA test as well as the mean of age, K1, K2, ACD, and AL measurements in relation to corneal astigmatism is shown in Table-IV. However, the mean of K1, K2 and Mean K were significantly more in the females than those in the males.

DISCUSSION

As the results of this study showed, based on clinical grading of cataract by anatomical location mixed cataract and mature cataract were the most common forms respectively and for the distribution of VA, the vision of counting finger with 66.1% of cases and light perception with 17.8% cases were the most common conditions. These findings are the indications of the patients' late approaching for cataract surgery in the area of Sabzevar, Iran. It may be due to their occupation since most of them, whether males or females, worked on the field or were male workers and female housekeepers. On the other hand these findings may confirm the need for a gross VA in these patients. Besides, the good vision of the fellow eye may have caused their late approaching for the cataract surgery procedure.

As for investigating the PXS, the results of this study showed that 36.4% of eyes had PXS and there were statically significant difference between

Table-IV: Mean distribution of Age, ocular biometry and corneal keratometry in terms of astigmatism.

Age (year) Keratometry Keratometry Anterior Axial

at principle at principle chamber

meridian one (D) meridian tow (D) depth (mm) length (mm)

No astigmatism 72.87+- 8.99 44,29+- 1.30 44.29+- 1.30 2.62+-0.30 22.83+- 0.79

Against the rule 70.88+- 9.80 45.2 1+-1.37 43.86+-1.78 2.68+-0.39 22.74+-0.81

With the rule 62.83+-11.91 44.11 +-1.39 45.15+-1.29 2.91+-0.36 23.39+-1.71

P-value less than 0.001 less than 0.001 0.001 0.003 0.031

patients with and without PXS for mean of age and IOL power. Also, the mean of ACD was shallower in age-related cataract patients with PXS than the other patients (p=0.049). This result is similar to the finding in the literature.3,15,16 However, explanations for this finding may be due to zonular weakness, type of cataract, anterior displacement of lens iris diaphragm and increased age.

But, present study did not show statically significant difference for mean of K1, K2, mean K, LT, VCD, AL and IOP between both groups with and without PXS. Study by Altintas17 for comparison of the IOP in 19 patients with PXS and 25-age matched and normal subjects showed that the mean IOP of PXS patients was significantly higher than the control group. This difference may be due to difference in age of subjects, sample size, ethnicity of the study population and other affecting factors. In present study investigation of ocular biometry was done in age related cataract patients with and without PXS. Furthermore, in this study corneal astigmatism was found in 72.9% of the patients and also the present study revealed that young age is a risk factor for corneal astigmatism and "against the rule" astigmatism is more likely to occur in older ages. In terms of gender, the mean of corneal power for K1, K2 and mean K were significantly more in females than those in males.

Similarly, a study by Shufelt et al14 on adult Latinos population revealed that corneal power is greater in females.

In conclusion, it seems that patients with age related-cataract along with PXS have shallower ACD, hence need greater IOL power and are older. Also, younger age in patients with age-related cataract can be considered as a risk factor for corneal astigmatism and "against the rule" astigmatism is more common in older ages.

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13. Wong TY, Foster PJ, Johnson GJ, Seah SK. Refractive Errors, Axial Ocular Dimensions, and Age-Related Cataracts: The Tanjong Pagar Survey. Invest Ophthalmol Vis Sci 2003;44:1479-1485.

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16. Zheng X, Sakai H, Goto T, Namiguchi K, Mizoue S, Shiraishi A, et al. Anterior Segment Optical Coherence Tomography Analysis of Clinically Unilateral Pseudoexfoliation Syndrome: Evidence of Bilateral Involvement and Morphologic Factors Related to Asymmetry. Invest Ophthalmol Vis Sci 2011;52:5679-5684.

17. Altintas O, Yuksel N, Karabas VL, Qaglar Y. Diurnal intraocular pressure variation in pseudoexfoliation syndrome. Eur J Ophthalmol 2004;14:495-500.

1. Ebrahim Shirzadeh, MD, Associate Professor of Ophthalmology, Sabzevar University of Medical Sciences, Sabzevar, Iran. 2. Arash Akaberi, MS, Faculty Member of North Khorasan University of Medical Sciences, Bojnurd, Iran. 3. Ma'ssoumeh Bemani Naeini, PhD, English Department, Mashhad Branch, Islamic Azad University, Mashhad, Iran. Correspondence: Ebrahim Shirzadeh, MD, Department of Ophthalmology, Vase'ee Hospital, Sabzevar University of Medical Sciences, Sabzevar, Iran. E-mail: dreshirzad@yahoo.com, Received for Publication: August 27, 2011, Revision Received: January 19, 2012, Revision Accepted: February 15, 2012
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Author:Shirzadeh, Ebrahim; Akaberi, Arash; Naeini, Ma'ssoumeh Bemani
Publication:Pakistan Journal of Medical Sciences
Article Type:Report
Geographic Code:9PAKI
Date:Jun 30, 2012
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