The role of axial length in central and branch retinal vein occlusion

BACKGROUND AND OBJECTIVE: To assess whether the axial length is a local risk factor in central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO). PATIENTS AND METHODS: The axial lengths of affected and fellow eyes of 19 patients with CRVO and 27 with BRVO and of their controls were measured with A-scan ultrasonography. The control group consisted of 17 individuals for CRVO and 25 for BRVO matched in age, sex and the prevalence of hypertension and diabetes in patient groups. The results of measurements in affected, unaffected and control eyes were compared. RESULTS: The mean axial length was different among the affected and unaffected eyes in patients with CRVO and their controls (P < .05). The affected eyes had significantly shorter axial length compared to the fellow and control eyes (P < .01 and P < .01, respectively). In the BRVO group, the mean axial length did not differ among affected, unaffected and control eyes (P > .05). CONCLUSIONS: Our study demonstrates a significantly shorter axial length in eyes with CRVO and not significantly shorter axial length in those with BRVO. The shorter axial length could be an additional risk factor in the pathogenesis of CRVO.     

Ocular structural changes in patients with Duane retraction syndrome: Does a correlation exist?

Purpose:The purpose of this study was to investigate the structural changes (axial length, central macular thickness (CMT), subfoveal choroidal thickness, and keratometry) in subjects with unilateral Duane retraction syndrome (DRS) as compared with the normal fellow eye.Methods:In this prospective study, we included 34 subjects with unilateral DRS from January 2016 to December 2016 seen at our institute. Data was collected for axial length, keratometry using partial coherence interferometry, CMT, subfoveal choroidal thickness using the enhanced depth imaging-optical coherence tomography (EDI-OCT). All these measurements were compared between the affected and fellow eye.Results:During this period, we included 34 subjects with unilateral DRS (22 Type I, 1 Type II, and 11 Type III). The mean age (±SD) of subjects was 14 ± 8 years (range: 5–28 years). There were 15 males and 19 females. Eyes with DRS were significantly shorter (median axial length 22.4 mm, interquartile range (IQR): 21.56 - 23.17) as compared to fellow eye (median axial length 22.7 mm, IQR: 22.35-23.55), P = 0.04. Choroidal thickness, CMT, and average keratometry were similar in DRS and fellow eyes (P = 0.39, 0.06, and 0.11, respectively). A significant difference in axial length was found only between Type I and Type III DRS (P = 0.03).Conclusion:This study suggests that in subjects with DRS, the affected eye has shorter median axial length when compared with the fellow eye. Prevalence of refractive error in eye with DRS was higher compared to fellow eye. But, there was no difference in magnitude of refractive error found between eye with DRS and normal fellow eye.     

轴长在视网膜分支静脉阻塞中的意义

目的评价眼轴长度（简称轴长）在视网膜分支静脉阻塞(branch retinal vein occlusion,BRVO)中的意义。方法34例BRVO和34例选自白内障摘除而年龄和性别相配的对照病例，做了轴长的对比研究，轴长应用A型超声测量。结果BRVO组患眼和对侧眼的轴长比较无统计学差异(P＞0.20)；BRVO组患眼轴长平均(23.16±0.82)mm，对照组眼的轴长平均(23.78±1.06)mm，两者差异无显著(P＞0.10)。结论作为远视眼依轴长测定结果并不是BRVO发病的一种危险因素。(中华眼底病杂志,1998,14:12-13)     

Relationship between anterior chamber depth, refractive state, corneal diameter, and axial length

PURPOSE: Phakic intraocular lenses are being used increasingly to correct refractive errors. We studied the relationship between anterior chamber depth, refractive state of the eye, spherical equivalent refraction, axial length of the globe, corneal diameter, and keratometry. METHODS: Two hundred eleven eyes of 211 patients were enrolled. All eyes underwent the same protocol with a complete ocular examination that included slit-lamp microscopy, intraocular pressure, objective and subjective refraction, calculation of the spherical equivalent refraction, corneal pachymetry, anterior chamber depth, axial length of the globe, and keratometry. All results were analyzed statistically using SPSS statistics software. Correlations between different parameters were studied using the Pearson correlation test. RESULTS: The anterior chamber depth was found to correlate significantly with both the average corneal diameter and the axial length of the globe (0.744, 0.531, P < .01) and was also found to correlate through an inverse relation with both age and spherical equivalent refraction (-0.391, -0.623, P < .01). Corneal thickness and keratometric power did not correlate with the anterior chamber depth. CONCLUSION: Most parameters (axial length, corneal diameter, spherical equivalent refraction, patient age) affected anterior chamber depth and should be considered carefully when planning refractive procedures that employ phakic intraocular lenses.     

Relation between retinal vein occlusions and axial length.

AIMS: To evaluate the ocular axial length as a risk factor for development of central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO). METHODS: Ocular axial lengths were measured, by A-scan ultrasonography, in 17 patients with CRVO and 41 patients with BRVO and compared with those of contralateral unaffected eyes and 66 age matched controls. RESULTS: In 17 patients with CRVO the mean axial length of affected eyes was 22.25 (SD 0.19) mm and of unaffected eyes was 22.61 (0.13) mm. In 41 patients with BRVO the mean axial length of affected eyes was 22.89 (0.11) mm and of unaffected eyes was 22.99 (0.12) mm. CONCLUSION: These findings confirm that the axial lengths in CRVO and BRVO were significantly shorter than in the controls. This significant difference may be a risk factor in the development of CRVO and BRVO.     

Biometric indices evaluation in central retinal vein occlusion using partial coherence laser interferometry

PURPOSE: To evaluate the association of axial length and posterior segment length with central retinal vein occlusion (CRVO) using optical coherence interferometry. METHODS: The study group consisted of 29 patients (13 female and 16 male) with unilateral CRVO who were referred to Farabi Eye Hospital. Patients with macular edema were excluded. The mean keratometry (mean K), axial lengths (AL), anterior chamber depths (ACD), and posterior segment lengths (PSL, defined by AL - ACD) of affected and fellow eyes were measured using optical coherence interferometry. RESULTS: Age range was 45 to 74 years (mean 59.2 +/- 7.5 years). The mean K of affected eyes was not statistically significantly lower than that of unaffected eyes in the CRVO group. This was also true for ACD. Although affected eyes had shorter axial length (23.26 mm vs 23.33 mm), the difference was not significant. There was a statistically significant difference in PSL affected and unaffected eyes (20.15 mm vs 20.26 mm) (p=0.008). CONCLUSIONS: Posterior segment length of eyes with CRVO may be shorter than unaffected eyes. This may predispose them to more crowding of central retinal vein and artery in lamina cribrosa, and developing CRVO.     

Retinoscopic (refractive) estimation of axial length in paediatric aphakia: a comparison with ultrasonic measurement

AIM: To compare paediatric axial length values estimated from the aphakic refraction alone with axial length values measured by ultrasound. METHODS: Retrospective institutional medical record review of paediatric aphakic patients 12 years of age and younger with documented ultrasonic axial length and objective refraction (retinoscopy) within 3 months of each other. An estimate of axial length was made from the aphakic refraction alone (with an assumed average keratometry value of 44 dioptres) for all patients. RESULTS: 149 eyes of 102 paediatric aphakic patients were identified. The ultrasonic axial length values (mean 22.47 mm, SD 1.69, 95% confidence interval (CI) 0.27) and estimated axial length values (mean 22.41 mm, SD 1.53, 95% CI 0.25) had an average difference of 0.05 mm (SD 1.04, 95% CI 0.17) and were not significantly different (p = 0.56) by the two tailed paired t test. A histogram of the differences that did exist between the two values resembled a normal distribution. The nine eyes with the largest differences between the two values had either low hyperopic aphakic refractions or abnormal average keratometry values. CONCLUSIONS: There was no significant difference between the two groups of axial length values, and the distribution of differences that did exist seemed random. The greatest differences between the two values occurred in longer (less hyperopic) eyes and in eyes with abnormally steep or flat keratometry. Estimation of axial length from the aphakic refraction alone seems to be a useful technique in the average paediatric eye, especially if biometry is unavailable.     

Refraction, axial length and age-related maculopathy

PURPOSE: To study the relationship between age-related maculopathy (ARM)/age-related macular degeneration (AMD) and phakic refraction and between ARM/AMD and axial length. METHODS: The study was a point prevalence study that included 663 randomly selected persons aged over 65 years. We measured axial length and refraction. Fundus images were graded for ARM according to a modified Wisconsin Age-related Maculopathy Grading System standard. Data from both eyes were available from most participants. We analysed the results for both individual eyes and pairs. RESULTS: The mean axial length was 23.22 mm for right eyes and 23.21 mm for left eyes. Women had a 0.57-mm shorter mean axial length than men. The mean refraction was +1.0 dioptres (D) for right eyes and +0.9 D for left eyes. At 70 years of age women were more hypermetropic than men by 0.66 D. There was no significant difference in refraction or axial length among the groups with different ARM stages. CONCLUSION: We found no statistically significant relationship between axial length/refraction and AMD/ARM. There was a statistically significant sex difference in axial length and refraction, where women had shorter axial lengths and were more hypermetropic than men.     

Accuracy of intraoperative retinoscopy in corneal power and axial length estimation using a high plus soft contact lens

AIM: To assess the accuracy of intraoperative retinoscopy with high plus soft contact lens (CL) in estimating corneal power and the axial length compared with standard keratometry and biometry measurement. METHODS: Intraoperative retinoscopy was performed in 30 eyes prior to the implantation of an intraocular lens (IOL). A +10 D disposable soft contact lens was applied on the cornea to minimize retinoscopic error. Corneal power was derived from refraction using biometric axial length while the axial length was derived using keratometric measurement. Refraction derived corneal powers and axial lengths from 26 eyes within +/-1.00 D of the target postoperative refraction were compared with preoperative standard keratometry and biometry measurements. RESULTS: In the 26 eyes, the mean difference between the corneal powers derived from refraction and keratometry was 0.35 D (S.D.=1.678). The 95% limits of agreement were -3.006 to +3.706. The mean difference between the axial lengths derived from refraction and biometry was 0.15 mm (S.D.=0.721). The 95% limits of agreement were -1.292 to 1.542. CONCLUSION: Intraoperative retinoscopy with a high plus soft contact lens after phacoemulsification is useful but not accurate in estimating corneal power or axial length of the eye. It should be used cautiously in IOL power calculation as a substitute for standard keratometry or biometry machines when either of these is not available or in error.     

Intraocular lenses in children: changes in axial length, corneal curvature, and refraction

AIM: To assess changes in axial length, corneal curvature, and refraction in paediatric pseudophakia. METHODS: 35 eyes of 24 patients with congenital or developmental lens opacities underwent extracapsular cataract extraction and posterior chamber intraocular lens implantation. Serial measurements were made of axial length, corneal curvature, objective refraction, and visual acuity. RESULTS: For patients with congenital cataracts (onset < 1 year age) the mean age at surgery was 24 weeks. Over the mean follow up period of 2.7 years, the mean increase in axial length of 3.41 mm was not significantly different from the value of an expected mean growth of 3.44 mm (paired t test, p = 0.97) after correction for gestational age. In the developmental cataract group (onset > 1 year of age) the mean age at surgery was 6.4 years with a mean follow up of 2.86 years. This group showed a mean growth in axial length of 0.36 mm that was not significantly different from an expected value of 0.47 mm (paired t test, p = 0.63). The mean preoperative keratometry was 47.78 D in the congenital group and 44.35 D in the developmental group. At final follow up the mean keratometry in the congenital group was 46.15 D and in the developmental group it was 43.63 D. In eyes followed for at least 2 years, there was an observed myopic shift by 24 months postoperatively of 3.26 D in the congenital cases (n = 10) and 0.96 D in the developmental cases (n = 18). CONCLUSION: The pattern of axial elongation and corneal flattening was similar in the congenital and developmental groups to that observed in normal eyes. No significant retardation or acceleration of axial growth was found in the eyes implanted with IOLs compared with normal eyes. A myopic shift was seen particularly in eyes operated on at 4-8 weeks of age and it is recommended that these eyes are made 6 D hypermetropic initially with the residual refractive error being corrected with spectacles.     

The Auckland Cataract Study: demographic, corneal topographic and ocular biometric parameters

Purpose : To determine patient demographics and the ocular biometric parameters in patients presenting for cataract surgery within the public hospital system, in a defined New Zealand population. Method : Prospective study of 502 eyes of 488 consecutive patients undergoing cataract surgery. A clinical assessment, including refraction, keratometry (K), A‐scan ultrasound and Orbscan II computerized topography was performed on each eye. Results : The mean age of the group was 74.9 ± 9.8 years (mean ± SD) with a female predominance (62%). Ethnic origin included 72% European, 8% Maori, 10% Pacific Islander, 4% Asian, 3% Indian and 3% other ethnic origins. The mean Log MAR visual acuity of eyes prior to cataract surgery was 0.88 ± 0.57 (approximately 6/48^–1). Corneal topographic (keratometric) maps were classified into five groups: 34% round, 10% oval, 31% symmetrical bow tie, 12% asymmetrical bow tie and 13% irregular. The mean steepest K measurement was 44.1 ± 1.7 D, the median keratometric astigmatism 0.89 D (range 0.0–6.5 D) and the steepest corneal meridian was horizontal in 50% and vertical in 43%. Seven per cent of corneas were spherical. Refraction revealed a mean sphere of 0.0 ± 3.1 D and a mean cylinder of –1.2 (range 0.0–7.5 D). Refractive astigmatism was with‐the‐rule in 15%, against‐the‐rule in 50% and oblique in 15%, with 20% spherical. Axial length was a mean of 23.14 ± 1.03 mm. Conclusion : Patients presenting for cataract surgery in this study were predominantly elderly, female, of European Caucasian ethnicity and exhibited relatively poor corrected visual acuity in the affected eye. Interestingly, 41% of eyes demonstrated bow‐tie topographic patterns, largely exhibiting with‐the‐rule astigmatism. However, assessment by keratometry or refraction highlighted against‐the‐rule more frequently; this may have implications for combined cataract and astigmatic surgery. The mean axial length was slightly shorter than expected for a group of predominantly European ethnic origin, although the mean refractive error was emmetropic.     

量化OCTA在视网膜静脉阻塞中的应用

目的:应用光学相干断层扫描血管成像技术(OCTA)测量视网膜静脉阻塞(RVO)患者黄斑区血流密度、黄斑中心凹无血管区(FAZ)面积和黄斑中心凹视网膜厚度。方法:选取RVO患者30例30眼,视网膜中央静脉阻塞(CRVO)和视网膜分支静脉阻塞(BRVO)患者各15例,双眼接受OCTA检查,获取黄斑中心3mm×3mm大小范围的血流密度、FAZ面积、黄斑中心凹视网膜厚度,以及双眼最佳矫正视力(BCVA)。比较患眼与健眼上述指标的变化及其与BCVA的相关性。结果:CRVO患者患眼黄斑区视网膜浅层毛细血管网(SVN)、深层毛细血管网(DVN)总血流密度较健眼降低[SVN:(43.07±4.95)%vs(50.09±2.86)%,DVN:(45.89±4.12)%vs(53.29±2.62)%,均P<0.01],与BCVA呈负相关(r_s=-0.6、-0.5,均P<0.05)。BRVO患者患眼SVN、DVN总血流密度较健眼降低[SVN:(45.62±3.04)%vs(52.10±2.98%),DVN:(49.21±3.80)%vs(55.52±3.33%),均P<0.01],与BCVA呈负相关(r_s=-0.5、-0.5,均P<0.05)。BRVO患眼病变区域与患眼未病变区域、健眼对应区域比较,SVN、DVN血流密度均下降(均P<0.01);患眼未病变区域DVN血流密度较健眼相应区域下降[(56.86±1.95)%vs(58.15±2.24)%,P=0.02];患眼病变区域DVN血流密度与BCVA呈负相关(r_s=-0.6,P=0.01)。CRVO、BRVO患眼SVN的FAZ面积较健眼明显扩大(CRVO:0.515±0.26mm²vs 0.27±0.08mm²,P<0.01;BRVO:0.376±0.12mm²vs 0.261±0.07mm²,P<0.01),且均与BCVA呈正相关(CRVO:r_s=0.6,P=0.01;BRVO:r_s=0.5,P=0.01)。CRVO、BRVO患眼黄斑中心凹视网膜厚度均较健眼增加(CRVO:431.2±191.3μm vs 235.5±18.2μm,P<0.01;BRVO:373.2±188.7μm vs 233.8±13.7μm,P=0.01),均与BCVA呈正相关(CRVO:r_s=0.9,P=0.01;BRVO:r_s=0.6,P=0.01)。结论:OCTA可作为测量RVO患者黄斑区血流密度、FAZ面积及黄斑中心凹视网膜厚度的有效工具。     

Axial Lengths in Children with Recessive Cornea Plana

Introduction: While flat keratometry contributes to the hyperopia and associated refractive accommodative esotropia that is part of recessive cornea plana, whether or not axial lengths are abnormally short in the disease is unclear. In this study we assess this possibility.

Methods: Prospective (2010–2012) axial length measurement (IOLmaster; Carl Zeiss, Oberkochen, Germany) of affected right eyes and comparison to right eyes with refractive accommodative esotropia only. Keratometry and refraction were also performed.

Results: For eight affected right eyes (age 10–12 years; seven families) axial length ranged from 21.46–24.80?mm (mean 23.34). Best corrected visual acuity ranged from 20/25 to 20/50, keratometry from 25.33–39.80 diopters (D) [mean 31.80], and refraction from +2.00 to +14.00 D (mean +7.22). For 50 control right eyes (age 4–12 years), axial length ranged from 19.87–23.66?mm (mean 21.6). Best-corrected visual acuity was 20/25 or better, keratometry ranged from 39.81–46.25 D (mean 42.42), and refraction from +2.25 to +8.00 D (mean 4.71). Axial lengths were longer in the affected group (2-tailed unpaired t-test p value 0.000005) despite greater hyperopia (2-tailed unpaired t-test p value 0.001).

Conclusions: Despite greater hyperopia, axial lengths were longer in eyes with recessive cornea plana, evidence that axial lengths are not shortened by the disease. Keratometry in children with cornea plana was below the range of controls and was the major factor underlying the phenotype's hyperopia.     

Central corneal thickness in congenital glaucoma

PURPOSE: The aim of this study was to compare central corneal thickness between eyes with congenital glaucoma and normal fellow eyes in unilateral glaucoma or less affected fellow eyes in bilateral glaucoma. METHODS: Eyes of consecutive phakic children with congenital glaucoma and previous glaucoma surgery were examined under chloral hydrate. Complete ophthalmologic examination, central corneal thickness (CCT), axial length, and corneal diameter measurements were performed. Patients were included in the study if presented with intraocular pressure (IOP) less than 21 mm Hg and no biomicroscopic signs of corneal edema. RESULTS: Nine patients were included in the study. The mean CCT in the more affected eye/glaucomatous eye was 522.3 +/- 65.2 microm and in the less affected eye/healthy eye was 579.7 +/- 44.5 microm. This difference was statistically significant (P = 0.0013). CONCLUSION: CCT was significantly thinner in glaucomatous eyes than in normal fellow eyes in phakic children with congenital glaucoma. This finding may be another confounding factor when measuring IOP in these patients.     

Retinal microcirculation correlates with ocular wall thickness, axial eye length, and refraction in glaucoma patients.

PURPOSE: To examine the correlations of refraction, axial eye length, and posterior eye wall thickness with retinal microcirculation. PATIENTS AND METHODS: In a prospective study, 25 patients with primary open-angle glaucoma, 12 patients with ocular hypertension, and 12 healthy subjects were examined; only one eye of each participant was considered in the analysis. Posterior eye wall thickness and axial eye length were measured with standardized A-scan ultrasonography. Retinal microcirculation temporal to the optic disc was determined by a scanning laser Doppler flowmeter using automatic full-field perfusion image analyzer software. RESULTS: In glaucoma patients, temporal retinal mean flow exhibited significant correlation to the eye wall thickness (r = 0.470, P = 0.042), axial eye length (r = -0.570, P = 0.011), and refraction of the eye (r = 0.520, P = 0.022). In glaucomatous eyes, the temporal retinal mean flow was significantly lower than in healthy subjects or in ocular hypertensive patients (P = 0.01). CONCLUSIONS: Myopic eyes have longer axial eye length and thinner ocular wall than emmetropic eyes. In glaucoma patients, the longer the axial eye length and the thinner the ocular wall, the more reduced the retinal microcirculation. The reduced microcirculation found in myopic glaucomatous eyes might contribute to the development of glaucomatous damage in these eyes.     

Axial length measurements after cataract surgery in adults

The purpose of the study was to check the difference in eye axial length before and after cataract surgery and to find out the possible correlation with refraction changes. The axial length was measured by ultrasound before and after cataract extraction with intraocular lens implantation. Keratometry measurements were also performed. The study comprised 32 eyes. The mean difference in axial length was 0.53 mm. The mean difference in keratometry was 0.37 D. There was no correlation between these values. CONCLUSION: The changes in axial length are not due to corneal curve changes. Perhaps in pseudophakic eyes different ultrasound velocity should be used.     

眼压和轴长在视网膜中央静脉阻塞中的意义

目的　探讨眼压和轴长在视网膜中央静脉阻塞中的意义。方法　应用TX- 10眼压计对4 6例(46只眼) CRVO患者的眼压进行测量。并使用A型超声仪对其中16例CRVO眼轴进行测量,对照组与病例组年龄和性别相配,例数相等。结果　36例CRVO阻塞眼眼压较对侧眼有不同程度降低。CRVO阻塞眼眼压显著低于对侧眼及正常对照眼(P <0 .0 1)。CRVO阻塞眼轴长显著短于对侧眼及正常对照眼(P <0 .0 1)。结论　CRVO可引起眼压降低,短眼轴是CRVO的危险因素。     

Retrospective evaluation of ocular axial length after unilateral cataract surgery with intraocular lens implantation in children and adolescents

PURPOSE: To evaluate the postoperative ocular axial length in children, who had unilateral cataract extraction with intraocular lens implantation. MATERIAL AND METHODS: In this retrospective study we studied 20 children (12 boys and 8 girls) in age from 7 to 20 years (mean 14 +/- 3.65 years), who had undergone surgery for unilateral cataract: 8 children had congenital cataract; 7 patients had traumatic cataract; in 5 cases there were secondary cataract: 3 children had cataract after uveitis, in 1 child cataract was due to steroid therapy because of nephrotic syndrome and 1 patient had neurodermatic cataract. In 16 cases PMMA lens was used, heparinized lens was implanted in 3 eyes and acrylic lens in 1 eye. The power of implants was from + 19 D to +24 D (mean 20.98 +/- 1.6 D). All measurements of axial length were obtained using ultrasound A scan. Examination was done from 14 months to 7.5 years after surgery (mean 3.5 +/- 1.55 years). The axial length in the operated eyes was compared with axial length of the fellow nonoperated eyes. RESULTS: Mean axial length in operated eyes was 22.58 +/- 1.56 mm. Mean axial length in fellow eyes was 22.96 +/- 1.42 mm. There were no significant differences between operated and nonoperated eyes (p>0.05). CONCLUSIONS: Cataract extraction with intraocular lens implantation does not influence rate of axial growth in children and adolescents.     

Manual keratometry and videokeratography after photorefractive keratectomy

PURPOSE: To examine the relative accuracy of manual keratometry and videokeratography in eyes treated by photorefractive keratectomy (PRK). SETTING: Eye Clinic, Cantonal Hospital, Lucerne, Switzerland. METHODS: Results of manual keratometry and videokeratography were compared with those of subjective refraction in 128 eyes before and 6 months after PRK. RESULTS: Six months after PRK, the mean subjective refraction of all eyes decreased more than the mean corneal dioptric power measured with videokeratography (P <.0001). The change in the mean subjective refraction compared with the corresponding difference in the mean manual keratometry of all eyes was also significant (P <.0001). CONCLUSIONS: This study confirmed an earlier observation that there is a disparity between the change in refraction and the reduction in corneal power measured by videokeratography and with the manual keratometer. Topographical changes from PRK and the subsequent wound-healing processes are likely to falsify objective measurements. The keratometric value in the center of the cornea, since it is not measured by manual keratometry and videokeratography, may actually be lower.