Comparison of biometric methods in young children with congenital cataracts in their eyes

BACKGROUND: Relevant keratometric and biometric indicators are necessary for intraocular lens (IOL) power calculation, which is difficult to verify in young children. AIM: Evaluation of the accuracy of various ultrasound methods and optical biometry for axial length measurement in young children with congenital cataracts. MATERIAL AND METHODS: Forty-six children (74 eyes) with congenital cataracts (43 eyes) and pseudophakia (31 eyes) at the age of 6 months to 4 years were examined. Various methods measured the axial length: ultrasound A-scan under general anesthesia by US-4000, ultrasound B-scan without general anesthesia by Voluson E8, and optical biometry by AL-Scan in cases of transparent optics. RESULTS: The greater axial length difference was observed between A-scan and optical biometry (less by 0,78 mm) than between B-scan and optical biometry (more by 0,27 mm). The median axial length difference between A-scan and B-scan was equal for infants and young children with congenital cataracts (0,525 mm and 0,535 mm, respectively). CONCLUSION: Axial length should be measured by different methods in young children with their further comparison to obtaining more accurate biometric indicators for IOL power calculation. The decrease of 12 mm in axial length, which occurs during the A-scan, can lead to errors in the IOL calculation of 36 diopters and unplanned refraction in the long-term period.

COMPARISON OF OPTICAL BIOMETRY AND A SCAN FOR CALCULATION OF INTRAOCULAR LENS POWER IN AGE RELATED NUCLEAR CATARACT AT TERTIARY CARE EYE HOSPITAL

Objective: To compare optical biometry and A-scan for calculating intraocular lens power in patients with nuclear cataract at tertiary care eye hospital. Study Design: Cross sectional comparative study. Place and Duration of Study: Armed Forces Institute of Ophthalmology, Pak Emirates Military Hospital, Rawalpindi, from Jul to Dec 2018. Methodology: In this study 70 eyes of 70 patients planned for cataract surgery by phacoemulsification underwent both optical biometry with intraocular lens master and ultrasound biometry applanation by A scan after informed consent. Intraocular lens power calculated by these two methods of biometry was compared. Phacoemulsification surgery was performed through a 2.3 mm superior temporal clear corneal incision. All patients underwent in the bag implantation of the same intraocular lens type. Results: The mean age of the patients was 62.89 ± 6.69 years. A significant (p-value<0.001) difference in intraocular lens power calculation was noted (20.96 ± 1.76 vs. 22.03 ± 1.61) with optical biometry and A-scan respectively. Association on the basis of age groups showed a significant (p-value<0.001) difference in both strata that was among patients having age ≤65 years and patients having age >65 years. Conclusion: Optical biometry was found efficient and safe method for calculation of intraocular lens power. Optical biometry is noncontact method having very less chance of infection and suitable for most of the eye types.