Mean Axial Length Of Eyes Research Articles

A comparison of IOLMaster 500 and IOLMaster 700 in the measurement of ocular biometric parameters in cataract patients

To compare the agreement of ocular biometric parameters measured by IOLMaster 500 and IOLMaster 700. This is a prospective study. IOLMaster 500 and IOLMaster 700 were used to measure the axial eye length (AL), corneal flat keratometry (Kf), corneal steep keratometry (Ks), mean keratometry (Km), corneal astigmatism(CA), J0, J45, anterior chamber depth (ACD) and corneal horizontal diameter (white-to-white distance, WTW) of 518 eyes (392 patients) with cataracts. Patients were enrolled unilaterally. Subgroup analyses were done according to the AL and Km. The intraclass correlation coefficient (ICC) and Bland–Altman analysis were used to evaluate the agreement. A total of 275 eyes were analyzed. The 95% confidence interval of ICC of the mean AL, Ks, Kf, Km, J0, and ACD values measured by the two instruments are indicative of excellent reliability (P < 0.001). The measurement results of WTW show good reliability (P < 0.001). The ICC of CA is of good reliability in CA < 0.5 D group (P = 0.000) and moderate reliability in the other two groups (P = 0.000). The WTW is the widest range among 95% consistency of the limit range measured by the two instruments. The results of IOLMaster 500 and IOLMaster 700 in measuring AL, keratometry, and ACD in cataract patients are of high agreement.

Accuracy of partial coherence interferometry in patients with large inter-eye axial length difference.

BackgroundTo determine accuracy of partial coherence interferometry (PCI) in patients with large inter-eye axial eye length (AEL) difference.MethodsPatients undergoing cataract surgery at two academic medical centers with an inter-eye axial eye length (AEL) difference of > 0.30 mm were identified and were matched to control patients without inter-eye AEL difference > 0.30 mm on the basis of age, sex, and AEL. The expected post-operative refraction for the implanted IOL was calculated using SRK/T, Holladay II, and Hoffer Q formulae. The main outcome measures were the refractive prediction error and the equivalence of the refractive outcomes between the subjects and controls.ResultsReview of 2212 eyes from 1617 patients found 131 eyes of 93 patients which met inclusion criteria. These were matched to 131 control eyes of 115 patients. The mean AEL was 24.92 ± 1.50 mm. The mean absolute error (MAE) ranged from 0.47 D to 0.69 D, and was not statistically different between subjects and controls. The refractive prediction error was equivalent between the cases and controls, with no significant difference between the MAE for any formula, nor in the number of cases vs. controls with a refractive prediction error of at least 0.50 D or 1.00 D.ConclusionsAmong eyes in our study population, good-quality PCI data was equally accurate in patients with or without an inter-eye AEL difference > 0.30 mm. Confirmatory AEL measurements using different AEL measuring modalities in patients with a large inter-eye AEL difference may not be necessary.

Intraocular Pressure Measurements in Standing Position with a Rebound Tonometer.

Background and Objectives: It has been established that body position can play an important role in intraocular pressure (IOP) fluctuation. IOP has been previously shown to increase significantly when lying down, relative to sitting; this type of investigation has not been extensively reported for the standing (ST) position. Therefore, this study aims to look for eventual significant IOP changes while ST, sitting, and lying down. Materials and Methods: An Icare PRO was used to measure the IOP of 120 eyes of 60 healthy individuals, with age ranging from 21 to 55 years (mean 29.22 ± 9.12 years), in sitting, supine and ST positions; IOP was measured again, 5 min after standing (ST-5m). Results: Mean IOP difference between sitting and ST position was 0.39 ± 1.93 mmHg (95% CI: 0.04 to 0.74 mmHg) (p = 0.027); between sitting and ST-5m, it was −0.48 ± 1.79 mmHg (95% CI: −0.8 to −0.16 mmHg) (p = 0.004); between the sitting and supine position, it was −1.16±1.9 mmHg (95% CI: −1.5 to −0.82 mmHg) (p < 0.001); between the supine and ST position, it was 1.55 ± 2.04 mmHg (95% CI: 1.18 to 1.92 mmHg) (p < 0.001); between supine and ST-5m, it was 0.68 ± 1.87 mmHg (95% CI: 0.34 to 1.02 mmHg) (p < 0.001); and between ST-5m and ST, it was 0.94 ± 1.95 mmHg (95% CI: 0.58 to 1.29 mmHg) (p < 0.001). Mean axial eye length was 24.45 mm (95% CI: 24.22 to 24.69 mm), and mean central corneal thickness was 535.30 μm (95% CI: 529.44 to 541.19 μm). Conclusion: Increased IOP in the ST-5m position suggests that IOP measurements should be performed in this position too. The detection of higher IOP values in the ST-5m position than in the sitting one, may explain the presence of glaucoma damage or progression in apparently normal-tension or compensated patients.

Refractive Outcome after Phacoemulsification Using Optical Biometry versus Immersion Ultrasound Biometry

Purpose: To compare refractive outcome after phacoemulsification using optical biometry versus immersion ultrasound biometry (US) .Patients and methods: A prospective, comparative, non-randomized interventional study included 100 eyes divided into 2 groups: Group (A): (Immersion US biometry) included 50 eyes. Axial Eye Length (AEL) was measured by immersion B scan (immersion A-scan with B- mode guided image). It was further subdivided into Group A1 (AEL ≥ 25 mm) and Group A2 (AEL < 25 mm). Group B (Optical biometry) included 50 eyes. AEL was measured using optical biometry. It was also subdivided into Group B1 (AEL ≥ 25) mm and Group B2 AEL < 25. Intra ocular lens (IOL) power was calculated using Haigis formula targeting post-operative refraction –0.5 to -1 D. Phacoemulsification with posterior chamber IOL was performed. The 2 groups were compared preoperatively for AEL, Keratometic measurements, uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA) and density of cataract. They were compared postoperatively for UCVA, BCVA, spherical equivalent (SE) and mean absolute error (MAE). Results: The study included (100 eyes). Group A1 included 9 eyes (18%) and Group A2 included 41 eyes (82%). Group B1 included 18 eyes (36%) and Group B2 Included 32 eyes (64%). Preoperative comparisons revealed insignificant statistical differences between the 2 groups in the mean AEL, IOL power, preoperative UCVA and BCVA, degree and density of cataract, and K readings. Post operatively there was insignificant statistical differences between the 2 groups in the mean of UCVA and BCVA. There was insignificant statistical differences between subgroups A1and B1 and subgroups A2 and B2 in the median of SE and MAE. Conclusion: The immersion B scan biometry and optical biometry gave comparative results with precise final post-operative refractive outcome.

Refractive Outcome after Phacoemulsification Using Optical Biometry versus Immersion Ultrasound Biometry

Purpose: To compare refractive outcome after phacoemulsification using optical biometry versus immersion ultrasound biometry (US) .Patients and methods: A prospective, comparative, non-randomized interventional study included 100 eyes divided into 2 groups: Group (A): (Immersion US biometry) included 50 eyes. Axial Eye Length (AEL) was measured by immersion B scan (immersion A-scan with B- mode guided image). It was further subdivided into Group A1 (AEL ≥ 25 mm) and Group A2 (AEL < 25 mm). Group B (Optical biometry) included 50 eyes. AEL was measured using optical biometry. It was also subdivided into Group B1 (AEL ≥ 25) mm and Group B2 AEL < 25. Intra ocular lens (IOL) power was calculated using Haigis formula targeting post-operative refraction –0.5 to -1 D. Phacoemulsification with posterior chamber IOL was performed. The 2 groups were compared preoperatively for AEL, Keratometic measurements, uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA) and density of cataract. They were compared postoperatively for UCVA, BCVA, spherical equivalent (SE) and mean absolute error (MAE). Results: The study included (100 eyes). Group A1 included 9 eyes (18%) and Group A2 included 41 eyes (82%). Group B1 included 18 eyes (36%) and Group B2 Included 32 eyes (64%). Preoperative comparisons revealed insignificant statistical differences between the 2 groups in the mean AEL, IOL power, preoperative UCVA and BCVA, degree and density of cataract, and K readings. Post operatively there was insignificant statistical differences between the 2 groups in the mean of UCVA and BCVA. There was insignificant statistical differences between subgroups A1and B1 and subgroups A2 and B2 in the median of SE and MAE. Conclusion: The immersion B scan biometry and optical biometry gave comparative results with precise final post-operative refractive outcome.

Comparison of measurements of the axial length of the eye using partial coherence interferometry and applanation ultrasound

Introduction Accurate biometry is an essential component of cataract surgery. Preoperative measurement of axial eye length (AEL), rather than the corneal curvature, is the most critical factor for accurate calculation of the intraocular lens (IOL) power [1]. Aim The aim of this study was to compare axial eye length (AEL) measured by applanation ultrasound (U/S) biometry versus that measured by partial coherence interferometry in eyes with clear crystalline lenses and eyes with cataract. Patients and methods A prospective, nonrandomized study included 60 eyes which were divided into two groups. Group I: 30 eyes with clear crystalline lenses. Group II: 30 eyes with cataractous lenses. Each group is further subdivided into three groups: group a with short AEL (&lt;22.00 mm), group b with average AEL (22.00–25.00 mm), and group c with long AEL (&gt;25 mm). Complete ophthalmological examination was performed for every patient. AEL was assessed by applanation A-scan U/S and optical biometry using partial coherence interferometry. Results A total of 60 eyes were included in the study. In group I (clear crystalline lens group), the mean AEL by applantion U/S biometry was 24.23±3.73 mm which is shorter than the mean AEL measured by optical biometry which is 24.48±3.66 mm and the difference is statistically highly significant (P=0.002). In group II (cataractous lens group), the mean AEL by applantion U/S biometry was 24.27±3.57 mm which is shorter than the mean AEL measured by optical biometry which is 24.46±3.43 mm and the difference between the two measurements was statistically nonsignificant (P=0.077). Conclusion Optical biometry provides longer mean measurements than applanation U/S biometry in eyes with cataract or clear lens, which is represented by a negative difference of 0.05 mm in AEL measurements. These results suggest that applanation A-Scan U/S biometry underestimates AEL.

Enlargement of the Axial Length and Altered Ultrastructural Features of the Sclera in a Mutant Lumican Transgenic Mouse Model.

Lumican (LUM) is a candidate gene for myopia in the MYP3 locus. In this study, a mutant lumican (L199P) transgenic mouse model was established to investigate the axial length changes and ultrastructural features of the sclera. The mouse model was established by pronuclear microinjection. Transgenic mice and wild-type B6 mice were killed at eight weeks of age. Gene expression levels of LUM and collagen type I (COL1) in the sclera were analyzed by quantitative real-time polymerase chain reaction (qPCR), and the protein levels were assessed by Western blot analysis. Ocular axial lengths were measured on the enucleated whole eye under a dissecting microscope. Ultrastructural features of collagen fibrils in the sclera were examined with transmission electron microscopy (TEM). Lumican and collagen type I were both elevated at the transcriptional and protein levels. The mean axial length of eyes in the transgenic mice was significantly longer than that in the wild-type mice (3,231.0 ± 11.2 μm (transgenic group) vs 3,199.7 ± 11.1 μm (controls), p<0.05 =). Some ultrastructural changes were observed in the sclera of the transgenic mice under TEM, such as evident lamellar disorganizations and abnormal inter-fibril spacing. The average collagen fibril diameter was smaller than that in their wild-type counterparts. These results indicate that the ectopic mutant lumican (L199P) may induce enlargement of axial lengths and abnormal structures and distributions of collagen fibrils in mouse sclera. This transgenic mouse model can be used for the mechanistic study of myopia.

Ultrasonography Findings in Eyes With Stage 5 Retinopathy of Prematurity.

To evaluate ultrasonography outcomes in eyes with stage 5 retinopathy of prematurity (ROP). Patients with bilateral stage 5 ROP were evaluated retrospectively. Ultrasonography examination was performed in all cases. Patients' demographic features and ultrasonography findings such as axial eye length, funnel configuration, subretinal hemorrhage, anterior loop traction, retinal cyst, and calcification were assessed, and correlations between variables were analyzed. Three hundred eyes of 150 patients were included. Sixty-one patients (40.7%) were female. The mean gestational age was 28.8 weeks ± 2.6 weeks, and the mean birth weight was 1,277 g ± 360 g. The mean axial eye length was 14.7 mm ± 1.8 mm. Two hundred forty-five eyes (81.7%) had closed-closed retinal detachment configuration, 32 (10.7%) had open-closed retinal detachment configuration, 17 (5.7%) had open-open retinal detachment configuration, and six (2%) had closed-open retinal detachment configuration. Subretinal hemorrhage (25.7%), anterior loop traction (24%), retinal cyst (2.3%), and calcification (1.3%) were also observed. Closed-closed funnel configuration, reduced axial diameter, and subretinal hemorrhage are associated with poor prognosis, and ocular ultrasonography examination for ascertaining these parameters is very important in cases with stage 5 ROP. In the present study, closed-closed retinal detachment configuration was noted in almost 80% of the cases with stage 5 ROP, which is probably the reason for the surgical failure in these end-stage cases.

Macular Bruch's membrane defects in Hi

AbstractPurpose To examine prevalence and associations of macular Bruch's membrane defects (MBMDs) in a population‐based setting.Methods The Beijing Eye Study 2011 included 3468 subjects with an age of 50+ years. MBMDs were defined as an interruption of Bruch´s membrane on the OCT images in the macular region.Results MBMDs could be detected only in highly myopic eyes (≤‐6 diopters or axial length of ≥26.5 mm). Prevalence of MBMDs in the highly myopic group was 17/164 (10.4±2.4%). Mean axial length of eyes with MBMD was 29.6±0.3 mm. Best corrected visual acuity of &lt;0.05 was found in 5 (29%) out of 17 eyes with MBMDs, and in 7 (41%) eyes, visual acuity was &lt;0.3 and ≥0.05. In the MBMD region, RPE and choriocapillaris were completely lost, and the deep and middle layers of the retina and the choroid were almost completely absent. In the MBMD region, mean retinal thickness was 153±57μm (range 20‐234μm) and choroidal thickness was 12.7±28.1μm (range 0‐88μm). On the fundus photographs, MBMDs appeared as whitish areas with round borders and without signs of RPE and choroid except of large choroidal vessels. In multivariate regression analysis, presence of MBMD was significantly associated only with longer axial length (P=0.002; Odds ratio: 3.87; 95% confidence interval: 1.64, 9.14).Conclusion MBMDs with a prevalence of about 10% in highly myopic eyes are associated with a complete loss of RPE and choriocapillaris, an almost complete loss of photoreceptors and choroid, and marked reduction in visual acuity. Characterized by a whitish fundus lesion with round borders, MBMDs can be differentiated from a chorioretinal atrophic lesion with Bruch´s membrane present. MBMDs may be added to the panoply of features of myopic maculopathy.

Using continuous intraoperative optical coherence tomography measurements of the aphakic eye for intraocular lens power calculation

Background/aimsTo include intraoperative measurements of the anterior lens capsule of the aphakic eye into the intraocular lens power calculation (IPC) process and to compare the refractive outcome with conventional IPC...

Predicting the Postoperative Intraocular Lens Position Using Continuous Intraoperative Optical Coherence Tomography Measurements

The aim of this study was to assess, if measuring the position of the lens capsule intraoperatively with a continuous intraoperative optical coherence tomography (OCT) device could be useful to improve the prediction of the intraocular lens (IOL) position. This prospective study included patients who were scheduled for cataract surgery. A prototype operating microscope with an integrated continuous OCT device was used to measure the anterior and posterior lens capsule position at different time points during cataract surgery. In all cases, a capsular tension ring (CTR) was used to tauten the lens capsule. Partial coherence interferometry was used to measure anterior chamber depth (ACD) immediately before, and 1 hour and 3 months postoperatively. Partial least squares regression (PLSR) was used to assess the influence of different pre- and intraoperatively measured parameters. In total, 70 eyes of 70 patients were included. Mean axial eye length was 23.6 mm (range, 20.6 mm-30.8 mm), mean used IOL power was 22.2 diopters (D; range, 6.0 D-31.5 D). PLSR showed that the anterior lens capsule measured after removing the crystalline lens and after implanting a CTR was a significantly better predictor for the postoperative ACD compared with preoperative ACD measurements. The main problem of IOL power calculation, the prediction of the IOL position after surgery, could possibly be reduced by using intraoperative lens capsule measurements instead of preoperative ACD measurements. (ClinicalTrials.gov number, NCT01867541.).

The effects of scleral buckling on young rabbit eyes.

To evaluate the effects of scleral buckling surgery on the developing eye in an animal model. Eleven young rabbits underwent scleral buckling surgery in one eye. In 6 rabbits, a 2.5 x 0.6-mm solid silicone encircling band (240 style) with a Watzke sleeve was used, and in 5 rabbits, a 2.0-mm silicone encircling sponge (502 style) with its ends abutting, but not connected, was used. After 3 months, both eyes of each animal were enucleated. Six eyes of an additional 3 rabbits served as baseline controls for determining initial globe volumes. Of the eyes buckled with a 240 band, 4 of 6 developed glaucoma compared with 0 of 5 eyes buckled with a 502 sponge (P =.06). Migration of the element occurred in all eyes with a 240 band (3 anterior, 3 posterior), while none of the 502 sponges migrated. There was no significant difference in the mean final corneal diameter between eyes with a 240 band (P =.94) and untreated fellow eyes or between eyes with a 502 sponge and untreated fellow eyes (P =.25). The mean axial length of eyes with a 240 band and untreated fellow eyes was 19.57 mm and 16.83 mm, respectively (P =.009). The mean axial length of eyes with a 502 sponge and untreated fellow eyes was 16.67 mm and 16.50 mm, respectively (P =.67). When comparing eyes with a 240 band with eyes with a 502 sponge, a significant difference was observed in the mean axial length (P =.006) and mean volume (P =.006) between the 2 scleral buckle groups. The use of a noninterrupted solid silicone encircling band appeared to have significant effects on the growth of young rabbit eyes. The use of an interrupted silicone sponge produced a buckling effect similar to the solid silicone band and did not migrate, adversely affect eye growth, or result in glaucoma. Noncontinuous encircling elements may prove to be as beneficial as continuous encircling elements in the treatment of tractional and rhegmatogenous retinal detachment in infant eyes without the potentially deleterious effects associated with a nondivided encircling band or the need for a second surgery to divide the encircling element.

Increase in Ocular Axial Length in Patients with Corneal Opacification

Seventy-nine patients were studied for corneal opacification and axial myopia. They were divided into three groups. One group had bilateral clear corneas; the second had unilateral corneal scars; and the third had bilateral corneal scars. A statistically significant difference was found in the mean axial length of eyes with bilateral corneal scars when compared with age- and sex-matched controls with normal corneas (P < 0.0001). In addition, there was a significant increase in the mean axial length of eyes with corneal scars when compared with their fellow eyes (P = 0.025).