Comparison of Anterior Segment Measurements Using Scanning-Slit Topography and Optical Low-Coherence Reflectometry (OLCR) Biometry

PURPOSE: To compare the results of anterior segment biometry including white-to-white (WTW) between scanning-slit topography (ORBscan IIz(R), Bausch & Lomb), optical low-coherence reflectometry (OLCR) biometry (Lenstar(R), Haag-Streit), and Castroviejo calipers. METHODS: Measurements on 72 eyes of 36 patients that underwent refractive surgery were measured using ORBscan(R), Lenstar(R), and calipers and compared. Ocular biometry parameters used in this study included the WTW, central corneal thickness, anterior chamber depth (ACD), keratometry, and pupil size. RESULTS: The WTW measurements using ORBscan(R) and calipers (11.57 +/- 0.35 mm and 11.58 +/- 0.34 mm, respectively) were statistically similar. However, the measurement using Lenstar(R) (12.05 +/- 0.40 mm) was significantly greater than with the other methods (p < 0.001). Central corneal thickness and keratometry measurements using ORBscan(R) were greater than when using Lenstar(R) (p = 0.01 for both). ACD and pupil size measurement using Lenstar(R) were greater than when using ORBscan(R) (p < 0.001 for both). CONCLUSIONS: Because WTW and ACD measurements using Lenstar(R) were greater than when using ORBscan(R) and calipers, unexpected high-vaulting may be observed due to the selection of a larger-sized posterior chamber phakic intraocular lens. Therefore, the differences in measurements obtained when using these methods should be considered.

Comparison of Anterior Segment Measurements Using Scanning-Slit Topography and Optical Low-Coherence Reflectometry (OLCR) Biometry

PURPOSE: To compare the results of anterior segment biometry including white-to-white (WTW) between scanning-slit topography (ORBscan IIz(R), Bausch & Lomb), optical low-coherence reflectometry (OLCR) biometry (Lenstar(R), Haag-Streit), and Castroviejo calipers. METHODS: Measurements on 72 eyes of 36 patients that underwent refractive surgery were measured using ORBscan(R), Lenstar(R), and calipers and compared. Ocular biometry parameters used in this study included the WTW, central corneal thickness, anterior chamber depth (ACD), keratometry, and pupil size. RESULTS: The WTW measurements using ORBscan(R) and calipers (11.57 +/- 0.35 mm and 11.58 +/- 0.34 mm, respectively) were statistically similar. However, the measurement using Lenstar(R) (12.05 +/- 0.40 mm) was significantly greater than with the other methods (p < 0.001). Central corneal thickness and keratometry measurements using ORBscan(R) were greater than when using Lenstar(R) (p = 0.01 for both). ACD and pupil size measurement using Lenstar(R) were greater than when using ORBscan(R) (p < 0.001 for both). CONCLUSIONS: Because WTW and ACD measurements using Lenstar(R) were greater than when using ORBscan(R) and calipers, unexpected high-vaulting may be observed due to the selection of a larger-sized posterior chamber phakic intraocular lens. Therefore, the differences in measurements obtained when using these methods should be considered.

Evaluation of Accommodating Potency of the Accommodative Intraocular Lens by Change of Anterior Chamber Depth

PURPOSE: To investigate the accommodating potency of the 1CU accommodative posterior chamber intraocular lens (PC IOL), according to pilocarpine-induced ciliary muscle contraction, near visual acuity, and distance-corrected near visual acuity after implantation of the IOL. METHODS: In a prospective study, 9 eyes of 7 patients (mean age 48+/-14.9 years [range 23 to 71 years]) had phacoemulsification and PC IOL (1CU(R), Humanoptics). Distance refraction, distance visual acuity (VA), distance-corrected VA (DCVA), near visual acuity (NVA), and distance-corrected near visual acuity (DCNVA) were determined at 2 week, 1, 2, 6, and 12 months after surgery. Anterior chamber depth (ACD) was measured 3 times with the Orbscan(R) (Orbtek, U.S.A.), and averaged. Then ACD was repeatedly measured within 90 minutes after administration of pilocarpine 2% eyedrops 3 times at 10 minutes interval. RESULTS At 2 weeks, 1, 2, 6 and 12 months after surgery, the mean DCNVA was 0.55+/-0.23, 0.37+/-0.14, 0.40+/-0.22, 0.51+/-0.20, and 0.56+/-0.20, respectively. The mean ACD decrease (mm) was 0.57+/-0.77, 0.91+/-0.69, 0.17+/-0.45, 0.35+/-0.40 and 0.59+/-0.31, respectively, using Orbscan(R) after pilocarpine 2% eyedrops. There was statistically significant correlation between the pilocarpine-induced IOL movement and DCNVA (r=0.439, P=0.012). CONCLUSIONS: 1CU accommodative PC IOL provided relatively good DCNVA and accommodating potency for up to 1 year. It is necessary to investigate accommodative change for a longer time period.

Evaluation of Accommodating Potency of the Accommodative Intraocular Lens by Change of Anterior Chamber Depth

PURPOSE: To investigate the accommodating potency of the 1CU accommodative posterior chamber intraocular lens (PC IOL), according to pilocarpine-induced ciliary muscle contraction, near visual acuity, and distance-corrected near visual acuity after implantation of the IOL. METHODS: In a prospective study, 9 eyes of 7 patients (mean age 48+/-14.9 years [range 23 to 71 years]) had phacoemulsification and PC IOL (1CU(R), Humanoptics). Distance refraction, distance visual acuity (VA), distance-corrected VA (DCVA), near visual acuity (NVA), and distance-corrected near visual acuity (DCNVA) were determined at 2 week, 1, 2, 6, and 12 months after surgery. Anterior chamber depth (ACD) was measured 3 times with the Orbscan(R) (Orbtek, U.S.A.), and averaged. Then ACD was repeatedly measured within 90 minutes after administration of pilocarpine 2% eyedrops 3 times at 10 minutes interval. RESULTS At 2 weeks, 1, 2, 6 and 12 months after surgery, the mean DCNVA was 0.55+/-0.23, 0.37+/-0.14, 0.40+/-0.22, 0.51+/-0.20, and 0.56+/-0.20, respectively. The mean ACD decrease (mm) was 0.57+/-0.77, 0.91+/-0.69, 0.17+/-0.45, 0.35+/-0.40 and 0.59+/-0.31, respectively, using Orbscan(R) after pilocarpine 2% eyedrops. There was statistically significant correlation between the pilocarpine-induced IOL movement and DCNVA (r=0.439, P=0.012). CONCLUSIONS: 1CU accommodative PC IOL provided relatively good DCNVA and accommodating potency for up to 1 year. It is necessary to investigate accommodative change for a longer time period.

A New Method for Measuring Corneal Refractive Power after Refractive Surgery

PURPOSE: To report a new method for measuring corneal refractive power after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) using the Orbscan(R) and autorefractokeratometer. METHODS: This study involved 12 cases that had undergone cataract surgery after corneal refractive surgery. Five cases had PRK and seven had LASIK. Keratometric values were evaluated with three different methods. The first, defined as RK, used an autorefractokeratometer (AK) (n=1.3375). The second, defined as K1, added the posterior surface diopter using AK and anterior surface diopter using an Orbscan. The last, defined as K2, added the posterior surface diopter and the anterior surface diopter using an Orbscan. Low K was a lower value between K1 and K2. RK, K1, K2 and Low K were compared with the back-calculated K value (Real K) 2 months after cataract surgery. RESULTS: The mean differences between RK, K1, K2, Low K and Real K were 3.08 +/- 0.98D, 0.41 +/- 0.66D, 0.27 +/- 0.77D, and -0.02 +/- 0.53D, respectively. In 9 of the 12 patients the difference was within 1D (75%) when either K1 or K2 was selected and in all patients, the difference between Low K and Real K was within 1D. CONCLUSIONS: The method of IOL calculation using Low K showed more accurate and predictable results in patients who had had cataract surgery after corneal refractive surgery.