Predicting Postoperative Anterior Chamber Depth in Cataract Patients Using Scheimpflug Slit Photography

Abstract

Purpose: To predict the postoperative anterior chamber (AC) depth from the preoperative in situ position of the lens central clear zone (CCZ) using Scheimpflug slit photography. Methods: 111 eyes of 78 cases that underwent phacoemulsification and intraocular lens (IOL) implantation were examined. 748 eyes of 383 healthy subjects with transparent lenses were used as the control. Scheimpflug slit photography was done under maximal mydriasis, and biometry was performed on the photographs. Two types of acrylic IOLs (MA30BA and MA60BM, both from Alcon) were used in this study. The preoperative AC depth (L1), the distance between the anterior lens capsule and lens CCZ (L2) and the postoperative AC depth (I1) were determined. I2, the predicted postoperative AC depth, was then determined from a linear regression of L1 + L2 and I1. Results: L2 thickened by 0.014 mm/year, and L1 decreased by 0.016 mm/year in the transparent lenses. L1 + L2 changed little with aging in both cataractous and transparent lenses. L1 + L2 and I1 showed a linear correlation with r = 0.80 in the MA30BA and r = 0.77 in the MA60BM groups. The mean error values between I1 and I2 were 0.095 ± 0.096 and 0.123 ± 0.114 mm in MA30BA and MA60BM, respectively. The error between I1 and I2 was within ± 0.17 and ± 0.33 mm or less in 72.9 and 91.5% of MA30BA and in 82.7 and 96.2% of MA60BM. In contrast, the error between I2 and I1 when calculated using the SRK/T formula was much larger – in excess of ± 0.33 mm in 38.7% of the eyes. Conclusions: L1 + L2 changes little with aging and is considered a useful marker of the position of the crystalline lens in situ. There was a high correlation between I1 and L1 + L2. These allow a far more accurate prediction of I1 than previous methods. In combination with the conventional regression formula and ray tracing, a highly accurate IOL power calculation can be attained.

Anterior chamber width measurement by high-speed optical coherence tomography

“…These include ultrasound A scan and B scan, slit scanning, Scheimpflug photography, and laser interferometry. [22][23][24][25][26][27][28][29][30][31] This study shows that OCT also is able to make this measurement very precisely. The interimage and interrater SD were 0, which means that the variation is less than our pixel depth (8.8 μm in aqueous).…”

Prediction of low-addition segmented refractive intraocular lens position and deviation using anterior-segment optical coherence tomography

“…The postoperative ACD formulae were previously published by Goto [ 14 ], Sasaki [ 15 ], Young [ 16 ], Haigis [ 25 ], and Retzlaff (SRK/T) [ 26 ] with r values of 0.791, 0.780, 0.720, 0.672, and 0.584, respectively. The new postoperative ACD formula was better than the published results ( Table 3 ).…”

“…Goto et al [ 14 ] reported that preoperative parameters such as ACD, AL, and ATA depth are extremely useful in predicting the postoperative ACD. Moreover, Sasaki et al [ 15 ] and Yoo et al [ 16 ] referred to CCZP and ELW, respectively, in their research.…”

“…The AL and ATA, adopted as the prediction parameters in our formula, are stable factors that are not highly susceptible to changes before and after a cataract surgery. Moreover, the CCZP remained at approximately the same position irrespective of age [ 15 ], and the age factor comprehensively supplemented the other factors. In other words, our formula considered the positional relationship between anatomically stable factors and postoperative ACD.…”