Effect Of Crystalline Lens Refractive Index Adjustment On Intraocular Lens Power Calculation In Patients With Dense Cataracts
Published 2024 - 42nd Congress of the ESCRS
Reference: PP05.10 | Type: Poster | DOI: 10.82333/bzaw-np27
Authors: Tsuyoshi Nogami* 1 , Takashi Kojima 2 , Akeno Tamaoki 3 , Ayako Sawaki 3 , Asato Hasegawa 3 , Tatsushi Kaga 3
1Department of Visual Sciences,Aichi Shukutoku Univesity Graduate School of Psychology & Medical Sciences Doctoral Course,Nagakute,Japan;Department of Visual Sciences,Aichi Shukutoku University Faculty of Health & Medical Sciences,Nagakute,Japan;Department of Ophthalmology, Japan Community Health Care Organization, Chukyo Hospital,Nagoya,Japan, 2Nagoya Eye Clinic,Nagoya,Japan, 3Department of Ophthalmology, Japan Community Health Care Organization, Chukyo Hospital,Nagoya,Japan
Purpose
The sum-of-segments (SOS) optical biometer, which uses the individual refractive index, has been widely used for assessing axial length before cataract surgery. The crystalline lens refractive index (CLRI) varies depending on the hardness of each ocular nucleus. However, the same CLRI (1.41) is applied to calculate the axial length (AL) when using SOS optical biometer. In this study, we evaluated the influence of CLRI on AL and predicted refractive errors (PRE), and aimed to propose an optimal CLRI in cases of dense cataracts.
Setting
Department of Ophthalmology, Japan Community Health Care Organization, Chukyo Hospital, Nagoya, Japan.
Methods
We assessed 298 patients (407 eyes) who underwent cataract surgery (average age, 78.2±8.8 y). They were classified into two groups based on the Emery-Little classification: Group A, with a nuclear hardness of ≤ III (358 eyes); and Group B, ≥IV (49 eyes). The SOS biometer (ARGOS®, Alcon, Fort Worth, Texas) was used for biometric measurements. Assuming the postoperative AL to be the correct value, a corrected CLRI (cCLRI) was calculated to make the preoperative AL equivalent to the postoperative one. The PRE of the SRK/T formula and Barrett Universal II (BUII) were evaluated using the pre- and post-correction refractive indices. The A constant was optimized in Group A, and the CNA0T0 or SN60WF (both from Alcon) was implanted.
Results
In Group A, the preoperative and postoperative ALs were 23.85±1.32 mm and 23.85±1.33 mm, respectively, with no statistically significant differences (p = 0.38). In Group B, the corresponding values were 23.78±1.63 mm and 23.76±1.63 mm, and the postoperative AL was significantly shorter (p<0.001). The average cCLRI in Group B was 1.42±0.01. For Group B, the predicted refractive errors (D) using cCLRI (SRK/T, 0.06±0.44; BUII, 0.20±0.41) were significantly smaller than those using CLRI (SRK/T, 0.12±0.45; BUII, 0.24±0.40)(p = 0.0013).
Conclusions
In cases where the crystalline lens nucleus hardness is ≥IV, using a value of 1.42 as the cCLRI may reduce predictive refractive errors.