Greater Anterior Chamber Depth Research Articles

Ophthalmic findings and reference values for selected ocular parameters in whooping cranes (Grus americana) and Mississippi sandhill cranes (Grus canadensis pulla).

To establish baseline ophthalmic parameters for an endangered, semi-wild population of healthy whooping cranes (Grus americana) (WHCR) and Mississippi sandhill cranes (Grus canadensis pulla) (SACR). Eighteen WHCR and 16 SACR. Ophthalmic examination was performed by a single observer, followed by conjunctival swab collection for aerobic bacterial culture and measurement of tear production (phenol red thread test, PRTT) and corneal diameter (CD) as tolerated. Measurement of the axial globe (AG) length, anterior chamber (AC) depth, lens thickness, vitreous chamber (VC) depth, and pecten length was performed via ocular ultrasound (OUS) as tolerated. Eyelid cicatrization (n = 1 WHCR), keratitis (n = 2 WHCR), incipient cataracts (n = 1 WHCR, n = 4 SACR), and uveal cysts (n = 1 SACR) were identified. Twenty-one bacterial species were cultured from SACR, while 18 bacterial species were cultured from WHCR. SACR under 6 months old had increased PRTT values compared to older SACR (p = .0432). AG length and VC depth of male WHCR were greater than in female WHCR (p = .0045 and p = .0008, respectively). WHCR less than 6 months old had greater AC depth and lens thickness than WHCR over 6 months (p < .001 and p = .0013, respectively). SACR less than 6 months old had greater AC depth and lens thickness than WHCR over 6 months (p < .0001 and p < .0001, respectively). WHCR and SACR are amenable to complete ophthalmic examination. Age-related differences in PRTT in SACR, sexual dimorphism in WHCR, and age-related differences in AC depth and lens thickness in WHCR and SACR were identified.

Associations between anterior segment biometry and high axial myopia in 3438 cataractous eyes in the Chinese population

BackgroundTo investigate the associations between anterior segment biometry and high axial myopia in cataractous eyes in the Chinese population.MethodsData on 3438 eyes from 3438 subjects were analyzed in this cross-sectional study. Anterior segment biometry, axial length measurements, and intraocular pressure evaluation were implemented using an Oculus Pentacam HR, a Zeiss IOLMaster 500, and a Nidek TonoRef II, respectively. A multivariate-adjusted logistic model and a multivariate-adjusted linear model were used for statistical analysis.ResultsThe mean age of the subjects was 62.2 ± 10.6 years, and 56.4% were female. There were 2665 subjects with high axial myopia (axial length, ≥26.50 mm) and 773 without (axial length, < 26.50 mm). The characteristics independently associated with high axial myopia included lower total corneal refractive power, a more negative Q value, greater total corneal astigmatism, greater white-to-white corneal diameter, greater anterior chamber depth, and higher intraocular pressure (all P < 0.05). In addition, greater axial length correlated with a thicker temporal cornea and a thinner nasal cornea (both P < 0.001).ConclusionsFor cataractous eyes, high axial myopia was associated with corneal flattening, increased total corneal astigmatism, anterior segment enlargement, and intraocular pressure elevation. The findings may inform the choice of intraocular lenses and the calculation of their power, help improve the surgical practice of refractive cataract procedures, and provide useful information on the centration and stability of intraocular lenses.

Axial Length and White to White Corneal Diameter in Eyes with Keratoconus

Abstract Objective To study the axial length (AL) and white to white (WTW) corneal diameter in keratoconus (KC) eyes and compare them to normal eyes. Methods Sixty-three eyes of 53 patients were included in this cross-sectional observational study divided into KC group comprised of 28 eyes of 18 patients and control group comprised of 35 eyes of 35 patients based on clinical and tomographic findings. All subjects were examined using rotating Scheimpflug corneal tomography (Pentacam HR; Oculyzer II) for central corneal thickness (CCT), thinnest corneal thickness (TCT), keratometric values, anterior chamber depth (ACD) and lens thickness, and by optical biometry (IOLMaster 500) for axial length (AL) measurements. Vitreous cavity length (VCL) was calculated by subtracting the values of CCT, ACD (internal), and lens thickness from the AL. White to white (WTW) corneal diameter was measured using Placido-based tomography (Topolyzer VARIO). Results The mean age was 31.27±8.65 years(30.39 ± 9.31) in the KC group and .(31.74 ± 8.38) in the non KC group. The KC group included 28 eyes their mean spherical equivalent (SE) was -3.16 ± 2.42 and the control group 35 healthy eyes including 23 ametropic eyes with mean spherical equivalent (SE) (-3.95±4.50 D) and 12 emmetropic eyes with mean SE (-0.19±0.40 D). The mean VCL was significantly greater in normal eyes (17.45 ±1.34 mm) compared with KC (16.77±1.18 mm) (P = 0.037), while the mean ACD (internal) was significantly greater in KC eyes compared to normal (P = 0.020) and the lens thickness showed no statistically significant difference. The greater VCL in the normal group was compensated by the greater ACD in the KC group causing the total AL to have no statistically significant difference (normal eyes =24.44 ±1.38 mm and KC eyes= 24.21 ±1.31 mm) (P = 0.513). There was no statistically significant difference in the WTW corneal diameter between KC and normal eyes (11.81 ±0.35 mm in the normal group compared to 11.79 ±0.35 mm in the KC group) (P = 0.835). Conclusion VCL was significantly greater in normal eyes compared with those eyes with KC. AL and WTW showed no difference between the two groups.

Iris surface features and anterior chamber depth in Chinese adolescents

BackgroundWe aim to determine the association of iris surface features including crypts, color and contraction furrows with anterior chamber depth (ACD) in a school-based sample of Chinese teenagers.MethodsTotally, 2346 students aged 13 to 14 years in Mojiang located in the Southwestern part of China contributed to this analysis. Iris surface features were graded based on standardized slit-lamp photographs. Ocular biometric parameters including ACD were measured using an IOL Master. Generalized estimating equation was incorporated in the linear regression models to assess the relationship between iris surface features and ACD.ResultsA significant trend of increasing ACDs with more contraction furrows were observed. On average, the mean ACD was 3.03 mm in participants with contraction furrows of grade 1 while it was 3.10 mm in those with grade 3 (mean difference, 0.07 mm, P = 0.01). Adjusting for other potential confounders such as gender, height and weight did not significantly changed the associations. Compared with individuals with contraction furrows of grade 1, those with grade 3 had a greater ACD of 0.06 mm (95% confidence interval: 0.01, 0.11) in multivariate-adjusted model. There were no significant relationships between ACD and iris crypts or color. (P > 0.10).ConclusionsMore iris contraction furrows are associated with greater ACDs while the association with iris color and crypts were not significant.

Clinical Analysis of Ocular Parameters Contributing to Intraoperative Pain during Standard Phacoemulsification.

Purpose. To study the correlation between ocular parameters and subjective pain that patients perceived during phacoemulsification. Methods. Medical records of 142 patients who underwent standard phacoemulsification under topical anesthesia between March and August 2016 were retrospectively reviewed. The pain during phacoemulsification and 1 h after surgery was assessed and compared using a visual analog scale. In addition, demographic data, preoperative biometric parameters, and intraoperative surgical parameters were recorded. Results. Mean age of patients was 67.49 ± 12.50 years. The mean pain score was 2.26 ± 0.85 during phacoemulsification and 0.40 ± 0.69 postoperatively. Intraoperative pain was significantly associated with higher preoperative intraocular pressure (β = 0.220, P = 0.016), greater anterior chamber depth (β = 0.210, P = 0.028), and greater axial length (β = 0.181, P = 0.043). Conclusions. To reduce the subjective pain when patients have high preoperative intraocular pressure, large anterior chamber depth, or great axial length, supplementary procedures may be required.

Comparing biometry in normal eyes of children with unilateral cataract/corneal disease to age-matched controls.

To compare ocular biometry and central corneal thickness of unaffected healthy eyes of pediatric patients with monocular cataracts/corneal opacities and age- matched controls. We studied 329 eyes of 329 children who were between 1 and 12 years old. The study group (n: 164) consisted of healthy fellow eyes of children operated for unilateral congenital/traumatic cataract and corneal laceration. Axial length, anterior chamber depth, lens thickness, vitreous chamber depth, and central corneal thickness were measured by ultrasound biometry/ pachymetry. Axial length was 22.16 mm in the study group and 21.99 mm in the control group. Anterior chamber depth, lens thickness, and vitreous chamber depth results were 3.35; 3.64 and 15.20 in the treatment group and 3.20; 3.63, and 15.15 mm in the control group, respectively. The axial length and all the components, i.e. anterior chamber depth, lens thickness, and vitreous chamber depth are higher in the unaffected healthy eyes of the pediatric patients than that of the control group but only the difference in the anterior chamber depth was statistically significant. The central corneal thickness was 548 microns and 559 microns in the study and the control groups, respectively, and the difference was found to be significant. Greater anterior chamber depth was chiefly responsible for the overall increase in the axial length in the study group. The central corneal thickness was significantly thinner in the study group than that of the control group. Keywords Ocular biometry; central corneal thickness; anterior chamber depth; lens thickness; vitreous chamber depth.

Interchangeability among five devices that measure anterior eye distances

PurposeThe aim was to study the interchangeability of various devices that measure anterior chamber depth (ACD) and white‐to‐white (WTW) distance.MethodsEighty right eyes of eighty patients aged 20 to 40 years were included. Their spherical equivalent ranged from ‐4.25 to +1.00 dioptres. Each eye's ACD and the WTW distance were measured using the following devices: a Castroviejo surgical calliper, CA‐200F Corneal Analyser, Orbscan II, Pentacam HR and IOLMaster 500.ResultsThe Pentacam HR measured significantly greater ACD (p < 0.01) than the other two devices, whereas IOLMaster 500 and Orbscan II yielded comparable (p > 0.01) distances. Nonetheless, in every device comparison, the mean difference was within clinically acceptable limits. The device comparison showed that for WTW distance measurements IOLMaster 500 yields the greatest value (p < 0.01), whereas CA‐200F Corneal Analyser yields the smallest one (p < 0.01).ConclusionPentacam HR, Orbscan II and IOLMaster 500 can be used interchangeably to measure ACD, whereas Orbscan II, IOLMaster 500, Castroviejo surgical calliper and CA‐200F Corneal Analyser cannot be considered interchangeable, when it comes to measuring WTW distance.

Ethnic Variation in Central Corneal Refractive Power and Steep Cornea in Asians

Purpose: To describe ethnic differences in the distribution of central corneal refractive power and steep cornea in a multiethnic Asian population.Methods: A total of 2968 Chinese, 2957 Indian and 2928 Malay participants aged over 40 years were included in this study. Each subject underwent standardized systematic and ocular examinations, interviewer-administered questionnaires, and blood investigations for risk factor assessment. Central corneal refractive power was measured using an autorefractor. Steep cornea was defined as central corneal refractive power exceeding 48 diopters (D) measured by keratometry.Results: Mean keratometry readings were 43.9 ± 1.5 D in Malays, 44.2 ± 1.5 D in Indians and 43.9 ± 1.5 D in Chinese. The prevalence of steep cornea was 0.6% (95% confidence interval, CI, 0.3–0.9%) in Malays, 1.0% (95% CI 0.7–1.4%) in Indians and 0.5% (95% CI 0.3–0.8%) in Chinese. In multivariate analysis, increasing central corneal refractive power was associated with Indian race, shorter body height, non-smokers, absence of pterygium, shorter axial length, thinner corneas and greater anterior chamber depth, while the presence of steep cornea was significantly associated with Indian race, shorter axial length and thinner corneas.Conclusions: Indian participants had the steepest corneas among the three major ethnic groups in Singapore. Central corneal refractive power was related to several ocular parameters including anterior chamber depth, axial length and central corneal thickness. These data have important clinical implications for understanding the risk of keratoconus.

Estudo do segmento anterior com a câmera rotatória de Scheimpflug em pacientes candidatos à cirurgia refrativa

To analyze the anterior segment of refractive surgery candidates and establish the variability pattern in this population regarding corneal volume, anterior chamber volume and depth and corneal thickness, using the noncontact three dimensional analyzer Pentacam. A retrospective study of 297 eyes of 149 patients was conducted using Pentacam. According to the spherical equivalent value two groups were created, myopia (n=242 eyes) and hyperopia (n=55 eyes), to analyze the variables of corneal volume, anterior chamber volume and depth and corneal thickness. The mean values of the myopia group were: corneal total volume 59.37 +/- 3.51 mm(3), corneal volume at 3 mm 3.87 +/- 0.23 mm(3), at 5 mm 11.31 +/- 0.67 mm(3), and at 7 mm 24.30 +/- 1.43 mm(3), anterior chamber volume 198.74 +/- 32.40 mm(3), anterior chamber depth 3.19 +/- 0.28 mm and corneal thickness 533.33 +/- 33.47 mm. In the hyperopia group, the mean total corneal volume was 60.77 +/- 3.31 mm(3), corneal volume at 3 mm from the apex was 4.01 +/- 0.20 mm(3), at 5 mm was 11.73 +/- 0.58 mm(3), and at 7 mm was 25.09 +/- 1.21 mm(3), the anterior chamber volume was 146.61 +/- 32.86 mm(3), the anterior chamber depth was 2.76 +/- 0.38 mm and the corneal thickness was 550.52 +/- 29.49 mm. The difference between the groups was significant for all variables (p<0.05). We observed in this study that patients with myopia had lesser mean corneal volume and pachymetry, and greater anterior chamber depth and volume compared with hyperopic patients.