Comparative study of axial length measurement using B scan and A scan biometry in intra ocular lens power calculation
Journal Title: Medpulse International Journal of Ophthalmology - Year 2019, Vol 9, Issue 3
Abstract
Abstract Background: Intra Ocular Lens power calculation are done preoperatively using different formulas like SRK-1, SRK-2, SRK-T, Holladay, Hoffer- Q, Haigis. They need Eye’s Axial Length (L)2, Corneal power (K)5, Estimated Lens Position post operatively (ELP) and A- constant for accurate IOL power (P) calculation to get emmetropic vision after surgery. Axial length of the eye ball can be measured by many methods like A scan, B Scan, OCT etc. Aim: To compare the accuracy of B-mode guided biometry with that of Contact A Scan biometry in preoperative IOL Power calculation and to assess the reproducibility while measuring the axial length of eye ball. Materials And Methods: Axial length of 50 eyes(Group A) were calculated using A scan contact biometry. In the other 50 Preoperative eyes(Group B) , B Scan were used to calculate the Axial length of eyeball . IOL power calculation were done for both groups using SRK -2 formula. For all these patients, cataract surgery were perfomed by Phaco emulsification method in the period of Feb 2015 till Jan 2016. Postoperative refractive status were calculated and tabulated after 45th postoperative day and comparison were done between both the groups. Results: Postoperative refraction for all 100 patients calculated and the details tabulated. The deviation of +/- 0.75Dsph and more of postoperative refraction is noted and tabulated. The axial length measured by B scan(22.9+1.3) was slightly longer than that measured by A-Scan(22.8+1.2). Postoperative refractive error showed mean of -0.045 in A Scan and-0.015 in B Scan. Postoperative refractive error showed Standard deviation of 0.43 in A Scan and 0.214 in B scan. Both the data’s are compared with paired t test and chi square test. Emmetropia is significantly higher in patients for whom IOL was implanted with the Axial length measured by B Scan(x2 =23.52, p=0.001) than the A Scan. Conclusion: Axial length measurement done by B Scan measurement gives less variation in readings and also better postoperative refractive stability compared to Axial length measurement done by A Scan biometry.
Authors and Affiliations
Venkatesan C, Sundara Rajan
Keywords
Related Articles
- EP ID EP536270
- DOI 10.26611/10099231
- Views 96
- Downloads 0
Tackling refractive surprise post cataract surgery – A surgeon’s nightmare
Cataract surgery is the most common surgery performed by ophthalmologists. The goal of surgery has shifted from restoring vision to providing a spectacle free vision. Refractive surprise post cataract surgery is one of t...
Comparative study of using fibrin glue and sutures in pterigyum excision with conjunctival autograft in tertiary care center
Background: Pterygium is a fibrovascular, wing shaped encroachment of the conjunctiva on to the cornea. The prevalence rates of pterygia range from 0.7 to 31% among different populations and are also influenced by age, r...
A study of prevalence of age related macular degeneration in patients >60 years of age attending OPD of ophthalmology in tertiary care hospital
Background: Age related maculopathy (ARM) is a degenerative disorder of the central area of the retina (the macula) often associated with visual impairment which is more frequent after 60 years of age. Aims and Objective...
A study on keratometry, axial length and IOL power among patients undergoing cataract surgery
For ocular examination there are three diagnostic aids namely, A-scan B-scan and M-scan with these techniques, several different systems for ultrasonically evaluating patients have been evolved. Independently either only...
Intraocular pressure after triamcinolone acetonide assisted anterior vitrectomy in patients with posterior capsular rent during cataract surgery
Aim of the Study: To study the postoperative intraocular pressure (IOP) and best corrected visual acuity (BCVA)after triamcinolone acetonide assisted anterior vitrectomy in patients who had posterior capsular rent during...