Iris-lens Contact Distance Research Articles

Structural and functional features of the eye in Marfan syndrome. Report 2. Changes in the anatomical complex of the lens

This study assesses the state of the anatomical complex of the lens in MS using UBM. The study was carried out on clinical material previously used by us to analyze changes in the fibrous membrane of the eye in MS. At the first stage, the main (19 patients with MS, 38 eyes) and the control (24 patients with myopia, 48 eyes) groups were formed for comparative evaluation. The formed groups were standardized according to the age of the patients and the axial length of the eye. At the second stage, patients with MS were divided into subgroups depending on the absence or presence of biomicroscopic signs of ectopia lentis (22 and 16 eyes, respectively). For UBM, an ultrasound linear sensor with a scanning frequency of 50 MHz was used (Aviso device, Quantel Medical, France). Various biometric UBM indicators were determined: lens thickness, diameter of the lens, lens-axial length factor, iris-lens angle, iris-lens contact distance, posterior chamber depth, length of the fibers of ciliary zonule, thickness of the ciliary body, sclera-ciliary process angle. There are changes in the anatomical complex of the lens as a whole in MS (in the lens itself, the ciliary zonule, and the ciliary body), which are characterized by an increase in lens thickness and a decrease in the diameter of the lens, an increase in the length of the fibers of the ciliary zonule and a decrease in the thickness of the ciliary body. At the same time, the displacement of the lens detected by optical biomicroscopy (ectopia lentis) can be considered as an advanced stage of changes in the anatomical complex of the lens. UBM provides the possibility of full-fledged visualization of all components of the anatomical complex of the lens in terms of both diagnostics, and monitoring of changes in MS. The question of the advisability of including this method in the algorithm for diagnosing ocular manifestations in order to verify the MS remains open. Possible obstacles may be, on the one hand, related to the need for special and expensive equipment, and on the other hand, the absence of a generally accepted «normal» values of UBM indicators of the anatomical complex of the lens.

Imaging analysis of the biological parameters of the lens in patients with cortical age-related cataracts using ultrasound biomicroscopy

BackgroundThe spatial position of the lens in patients with cortical age-related cataract (CARC) is unclear. We investigated a basis for the assessment of visual quality after cataract surgery by analysing the ultrasound biomicroscopic characteristics of the biological parameters of the lens in patients with CARC.MethodsIn this retrospective study, 119 patients (50 males and 69 females, totalling 238 eyes) with CARC who underwent simple cataract surgery were selected. The lens thickness (LT), axial length (AL), anterior chamber depth (ACD), lens vault (LV), trabecular-iris angle (TIA), iris-lens angle (ILA), iris-lens contact distance (ILCD) were measured by A-scan ultrasound and ultrasound biomicroscopy. The corresponding lens position (LP) and relative lens position (RLP) were calculated.ResultsLP was greater in men than in women (P < 0.05), LV was smaller in men than in women (P = 0.002), ILA and ILCD were not statistically significant (P = 0.072 and P = 0.854, respectively). There were significant differences in TIA, ILA, and ILCD in the four quadrants (all P < 0.05), with a trend in the distribution of TIA: superior < inferior < nasal < temporal, ILA: nasal < inferior < temporal < superior, and ILCD: superior < temporal < inferior < nasal.ConclusionsThe lens protrudes more obviously in females than in males and the lens tilts to a certain extent with the increase of age and tends to be more upward and temporal in the supine position. Therefore, trends in lens-related parameters in patients with CARC should be taken seriously.

Primary observations of EVO ICL implantation for high myopia with concave iris

PurposeTo investigate the morphological changes of concave iris in myopic patients after EVO implantable collamer lens (ICL) implantation.MethodsEVO ICL candidates with posterior bowing iris were observed using ultrasound biometric microscopy (UBM) in this prospective nonrandomized observational study. Forty patients were enrolled, with 20 patients in the concave iris group and the other 20 patients in the control group. None of the patients underwent laser peripheral iridotomy. All patients received preoperative and postoperative examinations, which included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), subjective manifest refraction and intraocular pressure. UBM was used to observe iris curvature (IC), irido-corneal angle (ICA), posterior chamber angle (PCA), iris-lens contact distance (ILCD), iris-zonule distance (IZD) and ciliary process length (CPL). Anterior chamber angle pigment was observed by gonioscopy. The preoperative and postoperative data were analyzed using SPSS.ResultsThe average follow-up period was 13.3 ± 5.3 months. The mean efficacy indices were 1.10 ± 0.13 and 1.07 ± 0.11 (P = 0.58), and the safety indices were 1.19 ± 0.09 and 1.18 ± 0.17 in the control group and the concave iris group (P = 0.93), respectively. The IOP postoperatively were 14.13 ± 2.02 mmHg and 14.69 ± 1.59 mmHg in control and concave iris groups (P = 0.37). Preoperatively, the concave iris group was presented with greater IC (P < 0.0001), longer ILCD (P < 0.0001), wider ICA (P = 0.004), narrower PCA (P = 0.01), and shorter IZD (P = 0.03) than the control group. In the concave iris group, IC, ILCD and ICA were significantly decreased after ICL implantation (P < 0.0001), while PCA and IZD were significantly increased (P = 0.03 and P = 0.04, respectively). Postoperative IC, ILCD, ICA, PCA and IZD were not statistically different between groups (P > 0.05). There was no significant difference in pigment deposition grades between the two groups (P = 0.37).ConclusionAfter EVO ICL implantation, the morphology of concave iris was significantly improved, which may reduce the risk of intraocular pigment dissemination caused by iris concavity. The concave iris has no impact on the safety of EVO ICL surgery during the follow-up.

Mechanical analysis of the impact of the morphology of the iris and ciliary body on the central vault after posterior chamber phakic intraocular lens implantation

Objective: To investigate the impact of the iris and ciliary body morphology on the central vault after phakic posterior chamber intraocular lens (pIOL) implantation. Methods: This research was based on the retrospective analysis of 123 patients (123 eyes) who underwent pIOL implantation in the Department of Ophthalmology, Affiliated Hospital of Qingdao University between June 2018 and June 2020. The anterior segment structure was observed with an ultrasound biomicroscope before surgery, and all morphological parameters of the iris and ciliary body were measured manually using the ImageJ software, including iris span (IS), iris convexity (IC), iris-ciliary body contact distance (ICCD) and iris-lens contact distance (ILCD). The ICCD was divided into Q1, Q2 and Q3 groups according to the equidistant distance of 0.36 mm. The lens thickness was measured with the IOLMaster. The horizontal corneal diameter and anterior chamber depth were measured using the Pentacam. The central vaults were measured by optical coherence tomography at 1 week, 3 months and 1 year after surgery. The relationships between vault values and preoperative parameters of the anterior segment were evaluated using the Pearson correlation analysis, Spearman correlation analysis, and multiple linear regression. The repeated measures ANOVA was applied to identify changes of vault values over time. Results: The mean values of the vaults at 1 week, 3 months and 1 year after surgery were (723±265) μm, (642±255) μm and (613±280) μm, respectively. The difference among them was statistically significant (F=50.143, P<0.001). The vaults continued to decline within 1 year after pIOL implantation, and the total decline was (122±86) μm. The vaults declined by (69±98) μm from postoperative 1 week to 3 months and by (52±54) μm from postoperative 3 months to 1 year. The regression formula showed that the pIOL size and ILCD were positively related with the vault, while the LT, IS and IC were negatively related with the vault at 1 week postoperatively (adjusted R²=0.404, P<0.001). The pIOL size and ILCD were positively related with the vault, while the IS and IC were negatively related with the vault at 3 months postoperatively (adjusted R²=0.342, P<0.001). The pIOL size was positively related with the vault, while the IS and IC were negatively related with the vault at 1 year postoperatively (adjusted R²=0.661, P<0.001). The vault values were higher in group Q3 compared to group Q1 at every timepoint, and the vault value was higher in group Q2 compared to Q1 at 1 year postoperatively. Conclusions: In the early postoperative period, eyes with a larger pIOL, shorter iris span, longer contact distance between the iris and ciliary body, and longer contact distance between the iris and lens were associated with a higher rate of excessive vaults. Meanwhile, eyes with a thicker lens and larger iris reverse convexity were more likely to obtain insufficient vaults. Within one year after surgery, the pIOL size, IS, IC and ICCD continued to impact on the vault. The ICCD, ILCD and IC can reflect the posterior chamber volume and change the haptic location and force, thus affecting the vault.

Comparison of Ocular Morphological Parameters Related to Lens Position by Anterior Segment Optical Coherence Tomography and Ultrasound Biomicroscopy.

Objective The objective is to compare parameters related to lens position measured using anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM) in patients with senile cataract and perform a consistency analysis. Methods This prospective study included 102 patients (102 eyes) scheduled for simple cataract surgery. Among the total patients, 44 were men, and 58 were women. AS-OCT (sitting) and UBM (lying) were used to measure the anterior chamber depth (ACD) in horizontal and vertical orientations and the iris-lens contact distance (ILCD) and iris-lens angle (ILA) in inferior, superior, nasal, and temporal quadrants. Paired-sample t-test was used to compare ACD, ILCD, and ILA measurements of the two methods, while Pearson's linear correlation and Bland-Altman analyses were used to analyze the correlation and consistency of the two results. Results The horizontal (2.499 ± 0.464 mm) and vertical (2.531 ± 0.463 mm) ACD measured using AS-OCT and the horizontal (2.556 ± 0.467 mm) and vertical (2.563 ± 0.479 mm) ACD measured using UBM were significantly different (P < 0.001); moreover, the results showed good correlation and agreement. A significant difference was observed between the two methods in terms of ILCD measured in inferior, superior, nasal, and temporal quadrants (P < 0.001), and a significant correlation was found between measurements of both methods (P < 0.001). Approximately 3.92% (4/102), 0.98% (1/102), 3.92% (4/102), and 2.94% (3/102) of points were outside the 95% limits of agreement in the four quadrants, respectively, and the agreement of the results was good. ILA measured using both methods differed in inferior, superior, nasal, and temporal quadrants (P=0.003, 0.011, 0.001, 0.001, respectively), and the correlation was good (P < 0.001). The percentage of points outside the 95% limit was higher in inferior, superior, nasal, and temporal quadrants (4.90% (5/102), 5.88% (6/102), 5.88% (6/102), and 6.86% (7/102)) with poor agreement of the results. Conclusions The correlation between AS-OCT and UBM in terms of measuring lens position-related parameters was good, but the agreement was unstable. The differences in measurement position (sitting and supine) and/or measurement methods (optics and ultrasound) may lead to variability in results.

Clinical analysis of anterior segment anatomic parameters of silicone oil tamponade eyes

Objective To analyse the anterior segment parameters of phakic eyes and aphakic eyes after silicone oil tamponade. Methods The data of 55 eyes of 55 cases with silicone oil tamponade and follow up≥3 months from Sep. 2017 to Dec. 2017 were collected and analyzed retrospectively. There were 35 phakic eyes and 20 aphakic eyes. The anterior segment parameters of all eyes were measured before and after surgery with ultrasound biomicroscopy. Results The angle opening distance (AOD500), trabecular-iris angle (θ1), trabecular ciliary process distance (TCPD) and iris-ciliary process distance (ICPD) of the phakic eyes after surgery were lower than those before surgery (P<0.05). The iris-lens contact distance (ILCD) and the angle between iris inner surface and anterior surface of lens (θ2) were increased after surgery compared with those before surgery (P<0.05). AOD500 and θ1 in aphakic eyes increased after surgery (P<0.05). ICPD in aphakic eyes decreased after surgery (P<0.05). Conclusion After silicone oil tamponade, the parameters related to the degree of opening of the ocular angle in phakic eyes are less than those before operation, while those of aphakic eyes increase. The pupillary block and iris distention in phakic eyes increase after silicone oil tamponade. The distance between iris and ciliary body of phakic eyes and aphakic eyes are shorter and the angle between sclera and ciliary body are smaller than those before surgery. Key words: Silicone oil tamponade; Anterior segment; Phakic eyes; Aphakic eyes

Assessment of the changes in anterior segment parameters by ultrasound biomicroscopy after laser peripheral iridotomy

Purpose The aim of this study was to evaluate the changes in anterior segment parameters by ultrasound biomicroscopy (UBM) after laser peripheral iridotomy (LPI) in eyes with narrow drainage angles. Patients and methods A prospective study was conducted on 20 eyes of 20 different patients with primary angle-closure glaucoma in need for LPI. Patients underwent a detailed ophthalmic examination including slit lamp examination, intraocular pressure measurement, and gonioscopy. UBM was performed before and 1 week after LPI. Quantitative parameters included angle-opening distance (AOD), iris thickness, trabecular-iris angle, trabecular-ciliary process distance, iris-lens contact distance (ILCD), and iridocorneal angle recess area (ICA). Results The mean age of the patients was 55±9.6 years (range: 40–80 years), and 12 patients were females. LPI was performed in the supero-temporal quadrant in 12 eyes and in the supero-nasal quadrant in eight eyes. On gonioscopy, none of the angle structures were seen on primary gaze in the four quadrants in two eyes, in three quadrants in eight eyes, and in two quadrants in 10 eyes. After LPI, ILCD increased significantly in 10 eyes (P Conclusion LPI significantly changed the morphology and parameters of anterior segment in eyes with narrow drainage angles, with obvious widening of the drainage angle. Unlike gonioscopy, these changes could be objectively highlighted and quantified accurately by UBM.

English

INTRODUCTION: Glaucoma is the second leading cause of blindness worldwide & is especially common & morbidity causing among women and Asians. Glaucoma afflicts 12 million people in our country. Primary open angle glaucoma is more common in general population. However angle closure glaucoma tends to be more aggressive & visually debilitating. Inspite of being treated with iridotomy, medical & surgical management, it continues to produce excessive visual morbidity. Acute angle closure glaucoma which is vision threatening is a potentially preventable condition and hence early identification and treatment with laser peripheral iridotomy in susceptible patients is of utmost importance. AIMS AND OBJECTIVES: To study the angle morphology before and after laser peripheral iridotomy in patients with primary angle closure & primary angle closure glaucoma. METHODOLOGY: Prospective observational study to study the changes in anterior chamber angle structures before and after laser peripheral iridotomy using Ultrasound biomicroscopic technique. The study was conducted in patients presenting to the glaucoma clinic of the department of ophthalmology of Govt Rajaji Hospital, Madurai for the period of 6 months. A total of 50 patients were studied. Patients presenting with shallow angles were studied & their complete history, assessment of anterior segment which includes slit lamp examination, gonioscopy by Goldman 3 mirror goniolens, IOP measurement by applanation tonometry, fundus examination using +90D lens and standard perimetry was done. The patients were categorised as Primary angle closure or as Primary angle closure glaucoma depending on the clinical findings. Then Ultrasound biomicroscopic assessment was done prior to and after 2 weeks of laser peripheral iridotomy to measure central ACD (anterior chamber depth), AOD (angle opening distance), TIA (trabecular iris angle) & other angle parameters. Results were analysed statistically. RESULTS: Among the total studied population of 50 patients, 48% were diagnosed to have primary angle closure & remaining 52% had primary angle closure glaucoma. In the PAC group: There was a significant change in all the parameters measured. ACD (mm) changed from an average from 2.199±0.04 to2.32±0.00 with a p value of ˂ 0.001. AOD 500 (Angle opening distance mm) increased from an average of 0.106 ± 0.0 to 0.209 ± 0.0 with a p value of ˂ 0.001. Sup TIA (deg) increased from an average of 8.252±0.16 to 16.081±0.23 with a p value of ˂ 0.001. Inf TIA (deg) increased from an average of 9.125±0.04 to 16.118±0.24 with a p value of ˂ 0.001. TCPD (TRABECULAR CILIARY BODY DISTANCE mm) increased from an average of 0.745 ± 0.0 to 0.82 ± 0.01 with a p value of ˂ 0.001. IT (IRIS THICKNESS mm) increased from an average of 0.459 ± 0.01 to 0.487 ± 0.00 with a p value of ˂ 0.001 ILCD (IRIS LENS CONTACT DISTANCE mm) decreased from an average of 1.217 ± 0.05 to 1.162 ± 0.02 with a p value of ˂ 0.001. ILA (IRIS LENS ANGLE deg) ) increased from an average of 25.729 ± 0.52 to 27.754 ± 0.57 with a p value of ˂ 0.001. In the Primary angle closure glaucoma group: There was no significant change in any of the measured parameters. CONCLUSION: Among the studied population, observation in the angle characteristics showed that there was statistically significant change in the UBM parameters noted in the primary angle closure group, however no such significant change was noted in the primary angle closure glaucoma group. Hence effective strategies should be adopted in order to identify angle closure at an early stage so that they can be treated prior to development of irreversible angle closure glaucoma.

Anterior Segment Morphology in Primary Angle Closure Glaucoma using Ultrasound Biomicroscopy.

AimTo evaluate the configuration of the anterior chamber angle quantitatively and study the morphological changes in the eye with ultrasound biomicroscopy (UBM) in primary angle closure glaucoma (PACG) patients after laser peripheral iridotomy (LPI).Materials and methodsA total of 185 eyes of 185 PACG patients post-LPI and 126 eyes of 126 normal subjects were included in this prospective study. All subjects underwent complete ophthalmic evaluation, A-scan biometry, and UBM. The anterior segment and angle parameters were measured quantitatively and compared in both groups using Student’s t-test.ResultsThe PACG patients had shorter axial length, shallower central anterior chamber depth anterior chamber depth (ACD), and anteriorly located lens when compared with normal subjects. Trabecular iris angle (TIA) was significantly narrow (5.73 ± 7.76°) in patients with PACG when compared with normal subjects (23.75 ± 9.38°). The angle opening distance at 500 pm from scleral spur (AOD 500), trabecular-ciliary process distance (TCPD), iris-ciliary process distance (ICPD), and iris-zonule distance (IZD) were significantly shorter in patients with PACG than in normal subjects (p < 0.0001). The iris lens angle (ILA), scleral-iris angle (SIA), and scleral-ciliary process angle (SCPA) were significantly narrower in patients with PACG than in normal subjects (p < 0.0001). The iris-lens contact distance (ILCD) was greater in PACG group than in normal (p = 0.001). Plateau iris was seen in 57/185 (30.8%) of the eyes. Anterior positioned ciliary processes were seen in 130/185 eyes (70.3%) of eyes.ConclusionIn PACG patients, persistent apposition angle closure is common even after LPI, which could be due to anterior rotation of ciliary body and plateau iris and overcrowding of anterior segment due to shorter axial length and relative anterior lens position.How to cite this article: Mansoori T, Balakrishna N. Anterior Segment Morphology in Primary Angle Closure Glaucoma using Ultrasound Biomicroscopy. J Curr Glaucoma Pract 2017;11(3):86-91.

Increased iris–lens contact following spontaneous blinking: Mathematical modeling

The purpose of this work was to study in silico how iris root rotation due to spontaneous blinking alters the iris contour. An axisymmetric finite-element model of the anterior segment was developed that included changes in the iris contour and the aqueous humor flow. The model geometry was based on average values of ocular dimensions. Blinking was modeled by rotating the iris root posteriorly and returning it back to the anterior. Simulations with maximum rotations of 2°, 4°, 6°, and 8° were performed. The iris–lens contact distance and the pressure difference between the posterior and anterior chambers were calculated. When the peak iris root rotation was 2°, the maximum iris–lens contact increased gradually from 0.28 to 0.34mm within eight blinks. When the iris root was rotated by 6° and 8°, the pressure difference between the posterior and anterior chambers dropped from a positive value (1.23Pa) to negative values (−0.86 and −1.93Pa) indicating the presence of reverse pupillary block. Apparent iris-lens contact increased with steady blinking, and the increase became more pronounced as posterior rotation increased. We conclude that repeated iris root rotation caused by blinking could maintain the iris in a posterior position under normal circumstances, which would then lead to the clinically observed anterior drift of the iris when blinking is prevented.

Anterior Segment Optical Coherence Tomography Analysis of Clinically Unilateral Pseudoexfoliation Syndrome: Evidence of Bilateral Involvement and Morphologic Factors Related to Asymmetry

To compare the morphology of the anterior chamber angle (ACA) and iris in eyes with pseudoexfoliation (PEX) syndrome to that of their clinically unaffected fellow eyes and normal control eyes. Forty-two patients with unilateral PEX syndrome and 42 normal subjects were studied. Eyes were separated into those with PEX, their clinically unaffected fellow eyes, and normal eyes. The dark-light changes of the ACA and iris were documented by anterior segment optical coherence tomography (AS-OCT) video recordings. The nasal ACA parameters including the angle opening distance at 500 μm (AOD500), the trabecular-iris space at 500 μm (TISA500), and the trabecular-iris angle at 500 μm (TIA500); anterior chamber depth (ACD); iris-lens contact distance (ILCD), and iris configuration were analyzed with the built-in software and a customized program. The ACA parameters were not significantly different among all three groups in the dark. The PEX eyes had significantly smaller ACA parameters than their fellow eyes and normal control eyes in the light. PEX eyes also had significantly shallower ACD, longer ILCD, and greater iris convexity (both in dark and light), and thinner iris (in dark) than their fellow eyes. The fellow eyes had significantly lower ACD both in the dark and light, and smaller angle opening distance at 500 μm and ILCD in the light than normal controls. There were no significant differences in the iris area among the three groups. Differences in the anterior segmental morphology are present between PEX and fellow eyes. These disparities may be related to the asymmetry in patients with the unilateral PEX syndrome.

New considerations on pupillary block mechanim

To study the mechanisms of pupillary block in eyes with occludable angle by ultrasound biomicroscopy. Initially, a pilot study of 13 eyes with acute primary angle-closure without medication was executed. Ultrasound biomicroscopy measurements of the angle, posterior chamber depth and iris thickness were performed in the temporal quadrant under light and dark conditions. Afterwards, ultrasound biomicroscopy measurements of iris-lens contact distance and iris-lens angle in the temporal quadrant and central anterior chamber depth were made in 32 eyes with acute primary angle-closure or intermittent primary angle-closure without medication, under light and dark conditions before and after laser peripheral iridectomy. In the pilot study, a significant decrease in the angle as well as a significant increase in the iris thickness occurred when comparing light to dark conditions. Before and after laser peripheral iridectomy (second study), significant differences were found in iris-lens contact distance (P<0.001) and iris-lens angle (P<0.001) under light and dark conditions. Also, significant differences were found in light and dark conditions, before laser peripheral iridectomy, in iris-lens angle (P=0.005), and after laser peripheral iridectomy, in iris-lens contact distance (P<0.001). No significant change occurred with anterior chamber depth. A decreased angle was correlated to an increase in iris thickness. After laser peripheral iridectomy, acute primary angle-closure or primary angle-closure eyes had an increased iris-lens contact distance and a decreased iris-lens angle. The anterior chamber depth did not change. These findings contradict the theory that pupillary block is the mechanism of acute primary angle-closure.

New comparative ultrasound biomicroscopic findings between fellow eyes of acute angle closure and glaucomatous eyes with narrow angle

To compare morphometric features between fellow acute primary angle-closure (APAC) eyes and glaucomatous or suspect eyes with narrow angle (NA). Fellow eyes of 30 patients with unilateral APAC and 30 with NA were evaluated by ultrasound biomicroscopy (UBM) under light and dark conditions. UBM parameters such as anterior chamber depth (ACD), angle opening distance at 250 microm/500 microm from the scleral spur (AOD250/AOD500), trabecular ciliary process distance (TCPD) and iris-lens contact distance (ILCD) were measured in the superior (SQ) and inferior (IQ) quadrants. Significant differences between APAC fellow and NA eyes were found in ACD, P<0.001; AOD250 at SQ and IQ, P<0.001; AOD500 at SQ and IQ, P<0.001; TCPD light, P=0.010 and TCPD dark at SQ, P=0.031; and TCPD light at IQ, P=0.010. Significant differences between light and dark examinations of APAC fellow eyes were found in ILCD (P=0.009) at SQ and ILCD at IQ (P=0.006), and of NA eyes in ILCD at SQ (P=0.047) and ILCD at IQ (P<0.001). APAC fellow eyes have a more crowded anterior segment and shallower ACD than NA eyes. ILCD decreases in both groups when the illumination conditions change from light to dark.

Ultrasound Biomicroscopy in Asymmetric Pigment Dispersion Syndrome and Pigmentary Glaucoma

To identify differences in anterior chamber anatomy among patients with asymmetric pigment dispersion syndrome and no other discernible cause for the asymmetry. Ultrasound biomicroscopy and A-scan biometry were performed on both eyes of 13 patients with asymmetric pigment dispersion syndrome without a known cause for asymmetric involvement. A radial perpendicular image in the horizontal temporal meridian detailing the scleral spur, angle anatomy, and iris configuration was obtained for each eye by 2 examiners. There were no differences in lens thickness (P = .33), refractive error (P = .84), or axial length (P = .99) between more and less affected eyes. However, the mean +/- SD iris concavity (P<.001), iris-lens contact distance (P = .02), and distance from the scleral spur to the iris insertion (0.42 +/- 0.11 vs 0.29 +/- 0.06 mm) (P = .002) were greater in the more affected eye of each patient. A more posterior iris insertion predisposes to the phenotypic expression of pigment dispersion syndrome.

Ultrasound biomicroscopic changes after laser iridotomy or trabeculectomy in angle-closure glaucoma.

This study was performed to demonstrate the ultrasound, biomicroscopic and dimensional changes of angle structure after laser iridotomy (LI) and primary trabeculectomy (PT) in primary angle-closure glaucoma (PACG). Angle-opening distance at a point 500 m from the scleral spur (AOD500), trabecular-iris angle (theta1), trabecular ciliary process distance (TCPD), ciliary process-iris angle (CPI), iris thickness (ID1, ID3), length of iris-lens contact distance (ILCD) and anterior chamber depth (ACD) were assessed before and after each procedure. Thirteen patients with LI and 16 with PT were prospectively enrolled. There were statistically significant increases in AOD500, theta1, and ILCD in both groups. CPI was decreased in both groups. ACD, TCPD, and iris thickness were not changed significantly. The changes in angle configuration after LI or PT may result more from alterations in aqueous pressure gradients across the iris and the changes of configuration were greater in the iris roots without rotation of ciliary body. However, we didn't find any significant differences in the changes of parameters between the two procedures.

Ultrasound biomicroscopic study of anterior segment changes after phacoemulsification and foldable intraocular lens implantation

Purpose To report quantitative changes in the anterior segment configuration after clear corneal incision phacoemulsification and foldable intraocular lens (IOL) implantation by means of ultrasound biomicroscopy (UBM). Design Prospective, nonrandomized, comparative (self-controlled) trial. Participants Twenty-one eyes of 19 patients with senile or presenile cataracts and no other ocular illness. Methods Patients were examined with UBM before and 1 and 3 months after surgery. At each UBM examination, axial images of the anterior chamber and radial sections of the angle at the superior, lateral, inferior, and medial quadrants were obtained. Main outcome measures Central anterior chamber depth (ACD), iris–lens contact distance, iris–lens angle (ILA), angle opening distance at points 250 (AOD250) and 500 μm (AOD500) from the scleral spur, trabecular–iris angle (TIA), iris thickness 500 μm from the scleral spur (IT), trabecular–ciliary process distance (TCPD), iris–ciliary process distance (ICPD), iris–zonule distance, iris–sclera angle (ISA), and ciliary process–sclera angle (CPSA). After surgery, central anterior chamber depth was also measured from the cornea to the IOL (ACD) and from the cornea to the pupillary plane (ACD2). Each variable was measured twice in different days by the same observer. Results The variables IT, TCPD, ICPD, IZD, and CPSA did not significantly change after surgery ( P > 0.01). Central anterior chamber depth increased approximately 30% after surgery (approximately 850 μm; P < 0.001), by both measurement methods used (ACD × ACD and ACD × ACD2). Anterior chamber angle significantly increased, by approximately 50% of the initial value, by the three measurement methods used: AOD250 ( P ≤ 0.002), AOD500 ( P < 0.001), and TIA ( P ≤ 0.003). The ISA increased by approximately 10° (30%) after surgery ( P < 0.001). The ILCD and ILA did not exist after surgery, except in two eyes. Conclusions After phacoemulsification and foldable IOL implantation, UBM revealed that the iris diaphragm shifted backward, deepening the anterior chamber by approximately 850 μm and widening its angle by approximately 10°. These findings may be of clinical significance in eyes with angle-closure glaucoma or with occludable angles.

Effect of mydriatic and cycloplegic drugs in glaucomatous and nonglaucomatous eyes using ultrasound biomicroscopy

Purpose: To study the anatomical relationships of the anterior segment of the eye, using ultrasound biomicroscopy in patients with chronic simple glaucoma and nonglaucomatous eyes, after mydriatic and cycloplegic instillation. Patients and Methods: Thirty eyes with chronic simple glaucoma and 30 nonglaucomatous eyes were studied. Anterior chamber depth, iris-lens contact and iris-zonule distance were measured, in both groups, using ultrasound biomicroscopy, in the three following conditions: without mydriatic and cycloplegic instillation, with 1% tropicamide alone and with 1% tropicamide plus 10% phenylephrine chlorhydrate. Results: Ultrasound biomicroscopy examinations of glaucomatous and nonglaucomatous eyes, without mydriatic and cycloplegic instillation, showed no statistically significant difference in the central anterior chamber depth, iris-lens contact and iris-zonule distance. The difference between examinations without mydriatic and cycloplegic instillation, with 1% tropicamide and with 1% tropicamide plus 10% phenylephrine chlorhydrate was statistically significant regarding the variables measured in both groups. Conclusions: No anatomical difference was observed between the anterior segment of glaucomatous and nonglaucomatous eyes after mydriatic and cycloplegic instillation. The results of this clinical investigation, using ultrasound biomicroscopy were innovative, allowing a dynamic and quantitative evaluation of the anatomical relationships between intraocular structures when submitted to mydriasis and cycloplegy, which up to now were only qualitative.

Effects of 0.2% Brimonidine on Ocular Anterior Structures

The aim of the study was to evaluate the effect of an alpha2-adrenergic agonist, 0.2% brimonidine, on a number of echobiometry and ultrasound biomicroscopy ocular parameters. Ten healthy subjects ranging in age from 20 to 40 years (mean age 29+/-3.39) were recruited into this prospective open-label trial. After instillation of 0.2% brimonidine eye drops, the following parameters were assessed: refraction, visual acuity, pupil diameter, intraocular pressure, five A-scan echobiometric parameters and 15 ultrasound biomicroscopy parameters. As early as the first hour after administration of the drug, a marked ocular hypotensive effect was detected associated with a miotic effect, without any refractive or visual acuity alterations. The A-scan echobiometry parameters were unchanged, while, as far as the ultrasound biomicroscopy variables were concerned, we observed an increase in iris-lens contact distance and a reduction in iris root thickness with a resulting increase in posterior chamber depth and in iris-ciliary process distances. No changes were observed in either the anterior chamber or the anterior iris profile. Brimonidine 0.2% proved to be an ocular hypotensive agent which is also endowed with a mild miotic effect, without giving rise to refractive or visual acuity alterations. The drug does not alter the thickness and position of the lens and does not facilitate pupil block; it reduces the iris thickness with an increase in posterior chamber depth and in iris-ciliary process distance but with no changes in anterior chamber depth or chamber angle width.

Iridolenticular contact decreases following laser iridotomy for pigment dispersion syndrome.

To evaluate changes in anterior segment anatomy after laser iridotomy for pigment dispersion syndrome. Ultrasound biomicroscopy was performed on 7 eyes of 7 untreated patients with reverse pupillary block and pigment dispersion syndrome. A radially oriented image with the probe perpendicular to the eye in the superior meridian was obtained before and at least 1 week after laser iridotomy in each eye. We assessed changes in angle recess area and iris-lens contact distance. Mean +/- SD patient age was 31.3 +/- 5.7 years and mean +/- SD refractive error was -5.0 +/- 3.9 diopters. Angle recess area (mean +/- SD, 0.78 +/- 0.28 vs 0.35 +/- 0.11 mm2; P=.001, paired t test) and iris-lens contact distance (2.05 +/- 0.28 vs 0.79 +/- 0.13 mm; P<.001) decreased following iridotomy. Central anterior chamber depth did not change. Flattening of the iris following laser iridotomy for pigment dispersion syndrome causes a decrease in iris-lens contact and angle width while lens position remains constant.

Ultrasound biomicroscopic morphometry of the anterior eye segment before and after one drop of pilocarpine.

To measure anterior eye-segment morphometric data using ultrasound biomicroscopy. This is a new high-frequency, high-resolution ultrasound method enabling the visualisation of the anterior segment of the living eye with magnification similar to a light microscope. Thirteen morphometric parameters of the anterior eye segment were measured before and after the application of one drop of pilocarpine in 10 eyes of 5 persons, using a Zeiss-Humphrey Ultrasound Biomicroscope at a frequency of 50 MHz. In each session, 3 morphometric parameters in the central images (corneal thickness, anterior chamber depth, pupillary diameter) were measured 4 times, and 10 parameters in the radial images (scleral thickness, angle-opening distance, trabecular-iris angle, trabecular-ciliary process distance [TCPD], iris thickness, 1, 2 and 3, iris-ciliary process distance, iris-lens contact distance [ILCD], iris elevation) were measured on the 3, 6 and 9 o'clock meridians three times each. Statistically significant changes were noted in the following parameters: pupillary diameter, iris thickness 1 and 2, and TCPD were decreased, while ILCD was increased after pilocarpine. Wide chamber angles showed a tendency to become narrower and narrow ones to become wider after pilocarpine. One drop of pilocarpine caused significant changes in the anterior eye segment morphology. Not only the pupillary diameter decreased but iris thickness and trabecular-ciliary process distance were also decreased simultaneously. At the same time the contact surface between the lens and iris increased significantly. Ultrasound biomicroscopy gives new morphometric image information about the anterior eye segment which is not available using conventional gonioscopy or ophthalmic echography.