Ultrasound biomicroscopic and conventional ultrasonographic study of ocular dimensions in primary angle-closure glaucoma

The plateau iris component of primary angle closure glaucoma: developmental or acquired

Primary angle closure glaucoma has been called the most common form of glaucoma in the world, and the leading cause of bilateral blindness. Pupillary block is felt to be the main mechanism of outflow obstruction in this condition. Recent advances in morphologic assessment of angle closure, specifically by means of ultrasound biomicroscopy, have revealed that plateau iris in eyes with angle closure glaucoma is more common than had previously been thought. The most characteristic finding in this disease is thicker and more anteriorly positioned lens. This induces the pupillary block that relives by laser iridotomy. Residual angle closure after laser iridotomy is due to the plateau iris. Peripheral iridoplasty, the standard treatment of plateau iris, tights the peripheral iris and opens the angle but has no effect on the ciliary processes configuration. The ciliary processes are positioned posteriorly after lens extraction but dose not disappears completely. Considering these facts we hypothesized that the plateau iris in primary angle closure glaucoma is a developmental entity that reaches to a critical stage with aging owing to the thickening and forward movement of the lens. Cataract surgery deeps the anterior chamber, widens the irido-corneal angle and reposits the ciliary processes posteriorly, so it can prevents synechia formation and progressive lens-induced angle narrowing and plateau iris progression, the acquired component, with aging.

Gender Variation in Ocular Biometry and Ultrasound Biomicroscopy of Primary Angle Closure Suspects and Normal Eyes

PURPOSE

To compare A-scan biometry and ultrasound biomicroscopy of primary angle closure suspects (PACS) with age-matched normal Indian eyes.

PATIENTS AND METHODS

Subjects with primary angle closure suspects (n=57 eyes) and normal eyes (n=57 eyes) underwent A-scan biometry and ultrasound biomicroscopy. Anterior chamber depth (ACD), anterior chamber angle (ACA), axial length (AXL), lens thickness, relative lens position (RLP), central corneal thickness (CCT), angle opening distance 500, trabecular-ciliary process distance (TCPD), iris-ciliary process distance, iris thickness, and scleral-ciliary process angle were measured. The subjects were divided into males, females, and combined groups for analysis. The parameters were compared using independent sample t test with Bonferroni correction for multiple comparisons.

RESULTS

In the combined group, the PACS subjects presented a significantly low ACD, AXL, CCT, AOD500, TCPD, ACA (P<0.001), and RLP (P=0.04). In males, RLP was anterior (P=0.002) and in females, the lens thickness (P<0.001) was significantly thicker among the PACS group.

CONCLUSIONS

ACD, AXL, CCT, TCPD, ACA, and angle opening distance 500 of the PACS group were significantly lower than in normals. In females, the lens in PACS was thicker than in normals. Lens in males was more anterior-placed in PACS group than in normals.

[Iridoschisis and angle-closure glaucoma: a case report]

INTRODUCTION

Iridoschisis is a rare condition where a localized area of iris stroma is cleaved in two, with the anterior atrophic portion disintegrating into fibrils. It is frequently associated with angle closure glaucoma and with cataract.

CASE REPORT

A 70-year-old male presented with reduction of visual acuity in the left eye. Visual acuity was 20/25 OD and 20/70 OS. He had suffered acute angle-closure glaucoma in the right eye 10 years before, treated with laser iridotomy and topical antiglaucomatous therapy. Intraocular pressure was 12 mmHg OD and 46 mmHg OS. Slit lamp biomicroscopic examination revealed bilateral shallow anterior chamber, iris atrophy, and leaf degeneration of the iris stroma. A-scan and B-scan standardized echography in both eyes showed shortening of the anterior chamber, a thickened and more anteriorly located lens, the presence of a few hyperechogeneous flocculated masses floating in the vitreous, and optic disc excavation.

CONCLUSION

The mechanism by which iridoschisis causes angle closure is unclear. A pupillary block could be favored by the thickening and anteriorization of the lens and the ciliary processes. Both the presence of strings of iris stroma occluding the trabecula and pupillary block could cause an elevation in intraocular pressure.

Optical coherence tomography of the anterior segment in secondary glaucoma with corneal opacity after penetrating keratoplasty

AIM

To evaluate secondary glaucoma after penetrating keratoplasty with anterior-segment optical coherence tomography (OCT).

DESIGN

Case series.

METHODS

Four eyes of four patients with corneal opacity and increased intraocular pressure (IOP) were evaluated using high-speed (2000 axial scans/s) OCT at 1.3 microm wavelength. Cross-sectional images of the anterior segment were analysed to assess the cause of increase in pressure.

RESULTS

Slit-lamp evaluation of the anterior chamber in all cases was limited by corneal opacity. The OCT imaging allowed visualisation of anterior-segment structures behind the opaque corneas. Using OCT, iris-intraocular lens adhesion and pupillary block were identified as the probable reasons for the increased IOP in one case. Peripheral anterior synechiae and angle closure were identified in the three remaining cases. In two cases, we found that the tip of the aqueous drainage tube was blocked by peripheral anterior synechiae.

CONCLUSIONS

OCT is similar to ultrasound in that it allows visualisation through opaque corneas. However, OCT has an advantage in that it requires neither contact nor immersion. It is a valuable tool for evaluating the depth of the anterior chamber angle and the causes of secondary angle closure.

Effects of small-incision phacoemulsification and intraocular lens implantation on anterior chamber depth and intraocular pressure

PURPOSE

To examine prospectively the effects of small-incision phacoemulsification and intraocular lens implantation (PEA+IOL) on anterior chamber depth (ACD) and intraocular pressure (IOP) using a newly developed scanning peripheral ACD analyzer (SPAC).

MATERIALS AND METHODS

Twenty-eight eyes of 21 patients who underwent PEA+IOL without any complications were examined and divided into 7 eyes each of grades 1 to 4 according to the Van Herick technique. The SPAC measured ACD consecutively from the vicinity of the pupil center to the periphery at 0.4-mm intervals. Changes in ACD and IOP as a result of PEA+IOL were investigated, and the factors contributing to the changes in ACD and IOP were examined.

RESULTS

PEA+IOL increased ACD significantly at all groups. The average changing rates were 3.19 +/- 0.67 times (Van Herick grade 1), 2.00 +/- 0.80 times (Van Herick grade 2), 1.92 +/- 0.32 times (Van Herick grade 3), and 1.36 +/- 0.65 times (Van Herick grade 4), respectively. The closer to the pupil center the measurement point was, the larger was the increase in ACD. However, the rates of increase in ACD were similar among the measurement points. The increases in ACD were significantly large in patients having a shallow preoperative ACD and a small optic axis length. The IOP reduction became significantly large in eyes with a shallow preoperative ACD.

CONCLUSIONS

The SPAC enabled quantitative measurement of changes in ACD from the vicinity of the pupil center to the periphery as a result of PEA+IOL. Changes in ACD resulting from PEA+IOL were thought to exert a greater effect on aqueous humor outflow facility as the postoperative ACD became shallower.

Anterior chamber measurements using Pentacam rotating Scheimpflug camera

PURPOSE

To investigate the mean values and standard deviations according to age, reliability, and correlation between different parameters of anterior chamber measurements using the Pentacam rotating Scheimpflug camera.

SETTING

Heidelberg IOL and Refractive Surgery Research Group, Department of Ophthalmology, University of Heidelberg, Heidelberg, Germany.

METHODS

This prospective clinical study comprised 76 healthy volunteers (mean age 46.6 years +/- 16.8 [SD]). Three consecutive measurements were made of only 1 eye and anterior chamber depth (ACD), mean and minimum anterior chamber angle (ACA), and anterior chamber volume (ACV) were evaluated.

RESULTS

Mean ACD was 2.93 +/- 0.36 mm, mean ACA was 34.81 +/- 5.05 degrees, minimum ACA was 29.99 +/- 5.53 degrees, and mean ACV was 160.3 +/- 36.81 mm3. Increasing age was associated with reduced ACD and ACV; however, mean and minimum ACAs were lowest in patients aged 40 to 59 years. Excellent correlation was found between ACD and ACV (R = 0.92). Anterior chamber depth and mean ACA correlated only moderately (R = 0.65). The correlation coefficient between ACD and minimum ACA was smaller (R = 0.58). There was no correlation between ACV and ACA (R = 0.37). Minor standard deviations were noted (ACD 0.02 +/- 0.02 mm, mean ACA 1.12 +/- 0.94 degrees, minimum ACA 2.04 +/- 2.67 degrees, and ACV 2.48 +/- 1.65 mm3).

CONCLUSIONS

Using the Pentacam, it was possible to examine different parameters of the anterior chamber within a short period and with good reliability. The evaluation of the ACA in different positions can help to classify the potential risk for angle-closure glaucoma.

Angle widening and alteration of ciliary process configuration after cataract surgery for primary angle closure

PURPOSE

To evaluate quantitatively, by means of ultrasound biomicroscopy (UBM), changes in the anterior segment configuration, including the ciliary processes, induced by cataract surgery in eyes with primary angle closure.

DESIGN

Retrospective interventional case series.

PARTICIPANTS

Thirty-one eyes of 31 patients with primary angle closure or primary angle-closure glaucoma were treated with cataract surgery. Before cataract surgery, 10 eyes had been treated with laser peripheral iridotomy, and 1 with laser peripheral iridoplasty.

METHODS

Configuration of the anterior chamber was examined by means of UBM before and at 3 months after cataract surgery.

MAIN OUTCOME MEASURES

Using UBM, anterior chamber depth (ACD), angle opening distance at points 500 mum from the scleral spur (AOD500), and trabecular-ciliary process distance (TCPD) were measured.

RESULTS

Not only ACD and AOD500, but also TCPD, increased significantly after cataract surgery, compared with measurements obtained before surgery (P<0.001). Postoperative AOD500 was correlated significantly with postoperative TCPD (r = 0.72, P<0.001) and with the amount of change of TCPD caused by cataract surgery (Delta TCPD) (r = 0.52, P<0.01).

CONCLUSIONS

Cataract surgery attenuated anterior positioning of the ciliary processes in eyes with primary angle closure, concomitant with significant widening of the angle. Cataract surgery resulted in not only complete dissolution of lens volume and pupillary block, but also attenuation of the anterior positioning of the ciliary processes, all of which contributed to postoperative widening of the angle in eyes with primary angle closure.

Ultrasound biomicroscopy of Chinese eyes with iridocorneal endothelial syndrome

AIM

To document the ultrasound biomicroscopic (UBM) findings in Chinese patients with iridocorneal endothelial (ICE) syndrome.

METHODS

21 patients with ICE syndrome and 15 normal subjects underwent UBM. UBM findings of anterior segment were compared between normal subjects and three clinical types of ICE syndrome: progressive iris atrophy (PIA), Chandler's syndrome (CS), and Cogan-Reese syndrome (CRS).

RESULTS

Central anterior chamber depth was significantly less in patients with ICE syndrome (2.25 (SD 0.32) mm) than in normal subjects (2.76 (0.32) mm). Peripheral anterior synechiae were observed in all the ICE patients by UBM. Three out of four CRS subjects showed an "arborised" shape of iridocorneal angle. Two eyes out of 10 with CS presented bridge-shaped synechiae. A membrane-like mound was observed in iridocorneal angle in two patients: one with CRS and one with CS. UBM was found to be more effective in detecting peripheral anterior synechiae (PAS) and iris atrophy than slit lamp microscopy and gonioscopy, mainly because of corneal oedema in patients with CS. Four out of 11 patients with unilateral ICE syndrome had shallow or closed anterior chamber angles in their fellow eyes. Two of them successfully responded to laser peripheral iridotomy.

CONCLUSIONS

UBM is an effective method to reveal the anterior segment features and provides a useful tool in the diagnosis of ICE syndrome. Different subtypes of ICE syndrome may have different UBM manifestations. UBM can help to identify angle closure in the fellow eye of unilateral ICE syndromes.

OCT-Goniometrie vor und nach Iridotomie beim Engwinkelglaukom

PURPOSE

Visualization of the anterior chamber angle is an important diagnostic method in patients with angle-closure glaucoma. In this study, optical coherence tomography (OCT) was used to image the angle width, the iris configuration, and the iris thickness in patients with angle-closure glaucoma.

METHODS

Thirteen eyes of 11 patients suffering from angle-closure glaucoma were studied with slitlamp-adapted OCT. All patients were treated with Nd:YAG laser iridotomy. The angle width ( degrees ), the angle opening distance (AOD) (microm), and the iris thickness (microm) were measured with OCT. The configuration of the iris was classified as steeply convex, convex, or flat.

RESULTS

The mean angle width was preoperatively 5.1+/-5.0 degrees (0-15 degrees ) and enlarged significantly (p=0.007) to 10.4+/-5.5 degrees (0-19 degrees ) postoperatively. The AOD changed from 71+/-55 microm (0-157 microm) preoperatively to 143+/-74 microm (0-256 microm) postoperatively (p<0.001). The mean iris thickness was 338+/-33 microm. With the exception of two eyes the predominant iris configuration changed from convex to flat.

CONCLUSIONS

OCT allowed visualization and noninvasive assessment of the anterior chamber angle region in patients with angle-closure glaucoma. Our results suggest that goniometry with OCT could improve the evaluation in patients with narrow or closed anterior chamber angles.

Ultrasound Biomicroscopy in the Subtypes of Primary Angle Closure Glaucoma

PURPOSE

To evaluate the anterior segment parameters in the subtypes of primary angle closure glaucoma (PACG) using ultrasound biomicroscopy.

METHODS

Five groups, each comprising 30 consecutive patients, diagnosed to have subacute PACG, acute PACG, chronic PACG, primary open angle glaucoma (POAG), and healthy controls were included in the present study. All patients underwent slit-lamp biomicroscopy, direct ophthalmoscopy, 90D fundus examination, gonioscopy, applanation tonometry, visual field testing, A-scan biometry, and ultrasound biomicroscopy (UBM). The anterior segment parameters recorded included: trabecular-iris angle, angle opening distance, trabecular ciliary process distance, and the iris thickness among other parameters.

RESULTS

On ultrasound biomicroscopy the trabecular iris angle of control and POAG groups was more than all the subtypes of PACG (P < 0.001). The trabecular iris angle of subacute PACG (P < 0.001) and chronic PACG (P = 0.003) was more than acute PACG. Angle opening distance of controls and POAG group was significantly more than acute PACG and chronic PACG (P < 0.001). The trabecular ciliary process distance of POAG group and controls was more than subacute PACG, acute PACG, and chronic PACG. The trabecular ciliary process distance of subacute PACG (P < 0.001) and chronic PACG (P < 0.001) was more than acute PACG. Eyes with acute PACG had the least iris thickness at the three different positions tested. There was a positive correlation between the anterior chamber angle (trabecular iris angle) and the following parameters: trabecular ciliary process distance, angle opening distance, anterior chamber depth, and the axial length (r = 0.57).

CONCLUSION

Eyes with primary angle closure glaucoma have a thinner iris with a shorter trabecular iris angle, angle opening distance, and trabecular ciliary process distance. The eyes with acute primary angle closure glaucoma have the narrowest angle recess.

Prevalence and mechanism of appositional angle closure in acute primary angle closure after iridotomy

PURPOSE

A prospective observational case series to assess the prevalence of appositional angle closure in darkness among iridotomized Chinese eyes after acute primary angle closure (APAC) with the use of both clinical methods and ultrasound biomicroscopy.

METHODS

Sixteen Chinese patients who had history of APAC and subsequent successful treatment with laser peripheral iridotomy were examined. Fourteen additional control subjects were studied. Gonioscopy and ultrasound biomicroscopic examination were performed in the dark. Gonioscopic appearance of the angle was assessed, and quantitative measurements of the angle from the ultrasound biomicroscopic images were taken.

RESULTS

Of the APAC eyes 55.6% had appositionally closed angle clinically and in 38.9% only Schwalbe's line was visible on gonioscopy. Ultrasound biomicroscopy confirmed structurally different anterior segments between eyes with APAC and the control eyes. In particular, the trabecular-ciliary-process distances were markedly different between the two groups.

CONCLUSION

This study documented a high prevalence of appositional closure in iridotomized eyes after APAC in Chinese patients. The anteriorly positioned ciliary body, as documented in these cases by ultrasound biomicroscopy, is the likely mechanism of the angle crowding in this patient population.

Cataract Surgery in Relative Anterior Microphthalmos

PURPOSE

To determine the prevalence of relative anterior microphthalmos (RAM) and evaluate intraoperative performance and surgical outcome in eyes with RAM undergoing cataract surgery.

DESIGN

Nested case-control series.

PARTICIPANTS

One thousand four hundred consecutive patients undergoing cataract surgery were evaluated to determine the prevalence of RAM. Relative anterior microphthalmos is defined as horizontal corneal diameter (HCD) < or =11 mm, anterior chamber depth (ACD) < or =2.2 mm, and axial length (AL) >20 mm, with no other morphologic malformation.

METHODS

Patients were examined preoperatively for HCD, ACD, and AL. Horizontal corneal diameter was measured with calipers. Anterior chamber depth and AL were measured with immersion shell with water. Associated ocular pathologic conditions were recorded. Two control groups were identified. Group I (normal eyes; n = 84) had HCD >11 mm, ACD >2.2 mm, and AL >20 mm. Group II (eyes with small corneal diameter; n = 84) had HCD < or =11 mm, ACD >2.2 mm, and AL >20 mm.

MAIN OUTCOME MEASURES

Patients with RAM and controls were evaluated for intraoperative performance and postoperative outcome. The 2-tailed Fisher exact test was applied to compare the performance of RAM with each of the control groups. The odds ratio (OR) with 95% confidence intervals (95% CI) was determined.

RESULTS

The prevalence of RAM was 6% (84 of 1400 eyes; 95%CI, 0.048-0.074). Relative anterior microphthalmos was associated with the presence of small pupil, 34 (40.48%); corneal guttae, 31 (36.9%); glaucoma, 29 (34.5%); and pseudoexfoliation, 6 (7.14%). Intraoperatively, RAM was associated with overall surgical difficulty because of less working space in 59 eyes (70.24%; OR, 63.7; 95% CI, 18.3-221; P<0.001) compared with control groups I and II; uveal trauma in 12 (14.28%); Descemet's detachment in 5 (5.95%); and posterior capsule rupture in 2 (2.38%). Postoperatively, RAM was associated with transient corneal edema in 63 eyes (75%; OR, 9.0; 95% CI, 4.4-18.0; P<0.001; OR, 5.4; 95% CI, 2.7-10.5; P<0.001) on the first postoperative day.

CONCLUSIONS

The prevalence of RAM was 6%. Relative anterior microphthalmos with its associations posed significant intraoperative difficulties. The occurrence of transient corneal edema was frequent.

Comparison of amplitude of apparent accommodation in pseudophakic eyes with that of normal accommodation in phakic eyes in various age groups

PURPOSE

To compare the amplitude of apparent accommodation in eyes with monofocal intraocular lenses with that of normal accommodation in the phakic fellow eyes in various age groups.

PATIENTS AND METHODS

In all, 130 eyes of 130 patients scheduled to undergo cataract surgery, and 130 fellow eyes that had little cataract and good visual acuity of 20/33 or better were studied. The following groups were studied: in their 40s and younger (n = 20) or in their 50s (n = 30), 60s (n = 30), 70s (n = 30), and 80s (n = 20). Using an accommodometer (Kowa HS-9E), the accommodative amplitude was measured at 1 month after surgery.

RESULTS

In the patients in their 40s and younger or in their 50s, the amplitude of apparent accommodation was significantly less than that of normal accommodation; no significant difference was observed in the patients in their 60s, 70s, or 80s. The incidence of patients in whom the amplitude of apparent accommodation was more than that of normal accommodation was greater in the patients in their 60s, 70s, and 80s than in the patients in their 40s and younger and in their 50s.

CONCLUSION

The amplitude of apparent accommodation is virtually equivalent to that of normal accommodation in patients older than 60 years of age.

The Effect of Laser Iridotomy on the Anterior Segment Anatomy of Patients With Plateau Iris Configuration

PURPOSE

To determine if laser iridotomy altered the anterior segment anatomy of patients with plateau iris configuration.

METHODS

Twenty eyes of 9 female and 1 male patients were imaged using an ultrasound biomicroscope within 19 weeks before and 52 weeks after laser iridotomy. Measurements obtained included the anterior chamber depth (ACD), trabecular-ciliary process distance (TCPD), iris thickness (IT), angle opening distance at 500 micrometers (AOD), iridozonular distance (IZD), and trabecular-iris angle (TIA). Comparisons of the pre- and post- iridotomy measurements were made using a two-tailed paired t test.

RESULTS

Laser iridotomy elicited no statistically significant change in ACD, TCPD, IT, AOD, or TIA. However, IZD was decreased (P < 0.05) in both eyes after laser iridotomy. Configuration of the irides was flat before and after laser iridotomies.

CONCLUSION

This study suggests that laser iridotomy did not alter anterior segment anatomy, probably because of the fixed anterior insertion of the iris and ciliary body in plateau iris configuration. The decrease in IZD distance may be the result of a small posterior movement of the iris due to a reduction in relative pupillary block, secondary to laser iridotomy. The small reduction in relative papillary block in plateau iris configuration does not alter the width of the anterior chamber angle as measured by AOD and TIA.

Prevalence of appositional angle closure determined by ultrasonic biomicroscopy in eyes with shallow anterior chambers

PURPOSE

To determine the prevalence of appositional angle closure in eyes with a shallow peripheral anterior chamber but no peripheral anterior synechia (PAS) in Japanese patients.

DESIGN

Cross-sectional study.

PARTICIPANTS

Eighty eyes of 80 consecutive patients with a shallow peripheral anterior chamber, determined using the method of van Herick, and no PAS.

METHODS

The anterior chamber angle was classified according to Shaffer's grading with noncompression gonioscopy superiorly, inferiorly, temporally, and nasally. The absence of PAS was confirmed by compression gonioscopy if necessary. The presence of appositional angle closure and the trabecular-iris angle (T-I angle) was determined with ultrasound biomicroscopy in each quadrant under light and dark conditions. Factors related to appositional angle closure were studied using logistic analysis, and the covariates included gender, age, refraction, gonioscopic grading, and the quadrant of the angle measured.

MAIN OUTCOME MEASURES

Gonioscopic grading of the angle width, the T-I angle, and the prevalence of appositional closure.

RESULTS

The gonioscopic grading (P<0.001 in light and dark) and the T-I angle (P<0.001 in light and dark) varied significantly among the 4 quadrants. Narrower angle gradings were observed more frequently superiorly. The T-I angle was narrower superiorly (in light) and inferiorly (in dark) (P<0.001 and P = 0.040, respectively). The T-I angle was significantly narrower in dark than in light (P<0.001). The sites with the narrower gonioscopic gradings tended to have a smaller T-I angle (P<0.001 and P = 0.006 in light and dark, respectively). Appositional angle closure was found in at least 1 quadrant in 46 (57.5%) of 80 eyes in light and in 68 eyes (85%) in dark. Logistic analysis showed that gonioscopic grading and the quadrant were significantly related to the presence of appositional angle closure in light and dark (P<0.003 for both comparisons).

CONCLUSIONS

Appositional angle closure was frequently observed in eyes with a shallow peripheral anterior chamber, especially under dark conditions in Japanese patients. The angle width, evaluated with conventional gonioscopic grading, and the quadrant of the angle were significantly related to the presence of appositional angle closure.

Comparison of Tilt and Decentration between Phacoemulsification and Phacotrabeculectomy

PURPOSE

To determine the extent of intraocular lens (IOL) tilt and decentration values after combined surgery in patients with cataract and glaucoma.

MATERIALS AND METHODS

A total of 106 cataractous eyes undergoing IOL implantation were divided into 2 groups. Group 1 comprised 42 eyes undergoing phacotrabeculectomy surgery for cataract and primary open-angle glaucoma (POAG), and group 2 comprised 64 eyes undergoing phacoemulsification surgery for senile cataract. The length of IOL decentration and the angle of IOL tilt were quantitated by using Purkinje reflections and photographic documentation.

RESULTS

The differences regarding both the IOL tilt (2.84 +/- 0.37; 2.97 +/- 0.37, respectively) and decentration (0.39 +/- 0.27; 0.49 +/- 0.35, respectively) was insignificant (p > 0.05) between groups.

CONCLUSION

There is no increased effect of phacotrabeculectomy on tilt and decentration of IOLs in eyes with POAG when compared with eyes which underwent phacoemulsification surgery.

Ultrasound biomicroscopic changes during accommodation in eyes with accommodating intraocular lenses

PURPOSE

To document ciliary body constriction and movement with the Crystalens AT-45 intraocular lens (IOL) (eyeonics) using ultrasound biomicroscopy.

SETTING

Eye Clinic, Department of Neurological and Visual Sciences, University of Verona, Verona, Italy.

METHODS

Patients with no preexisting ocular conditions other than cataract who agreed to return for follow-up were considered. Twenty eyes of 14 patients with a best corrected visual acuity of 5/10 or worse and a refractive error (spherical equivalent) of +/-1.0 diopter (D) had implantation of a Crystalens AT-45 accommodating IOL. Six patients had bilateral implantation. Ultrasound biomicroscopy was performed postoperatively at 1 and 6 months. Before and during accommodation, the anterior chamber depth (ACD) was measured to assess the endothelium-IOL distance and measure the scleral-ciliary process angle to determine whether there was anterior rotation of the ciliary body. The uncorrected distance acuity, best corrected distance acuity, uncorrected near acuity, distance corrected near acuity, best corrected near acuity, and accommodative amplitude were determined. Analysis was done to determine whether there was a correlation between the accommodative amplitude and the percentage variation in the ACD and scleral-ciliary process angle.

RESULTS

All surgical procedures were uneventful. The mean uncorrected distance acuity at 1 month was 0.8 +/- 0.14 (SD) and remained stable at 6 months. Three of 20 eyes (15%) and 8 of 20 eyes (40%) had a Jaeger acuity of J1 and J3, respectively, without additional power correction. During accommodation, the mean reduction in ACD was 0.32 +/- 0.16 mm at 1 month and 0.33 +/- 0.25 mm at 6 months. The mean narrowing of the scleral-ciliary process angle was 4.32 +/- 1.87 degrees at 1 month and 4.43 +/- 1.85 degrees at 6 months. There was a correlation between accommodative amplitude and a decrease in the ACD (r=0.404) and a decrease in scleral-ciliary process angle (r=0.773).

CONCLUSIONS

Anterior displacement of the Crystalens IOL and corresponding anterior rotation of the ciliary body occurred during near vision. The IOL displacement and rotation were proportional to the accommodation capacity.

A review of trabeculectomy in East Asian people—the influence of race

Glaucoma is the leading cause of irreversible blindness worldwide. East Asians account for approximately half of all glaucoma sufferers. It is likely that trabeculectomy will be needed for many of these people as the intraocular pressure is to be maintained at a satisfactorily low level. The eyes of East Asian people differ in some aspects from those of other races. This review describes the natural history of the eye after trabeculectomy in East Asians.

Anterior segment imaging: ultrasound biomicroscopy

Ultrasound biomicroscopy technology has become an indispensable tool in qualitative and quantitative assessment of the anterior segment. Advances in soft-ware design and algorithms will improve theoretical understanding of the pathophysiology of anterior segment disorders. Future applications of quantitative techniques will yield important information regarding mechanisms of angle closure, improving understanding of the dynamic functions of the iris,accommodation, presbyopia, and other aspects of anterior segment physiology and pathophysiology.

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.

Five-year risk of progression of primary angle closure to primary angle closure glaucoma: a population-based study

OBJECTIVE

To report the 5-year progression to primary angle closure glaucoma (PACG) in a population-based cohort of primary angle closure (PAC) subjects.

METHODS

A total of 37 patients diagnosed as PAC during a population-based study in 1995 were invited for re-examination in 2000. Patients underwent a complete ophthalmic examination including ocular biometry. Progression to PACG was based on optic disc damage and field defects on automated perimetry.

RESULTS

In all, 28 of 32 PAC subjects who could be contacted presented for examination. Eight (28.5%; 95% CI 12-45%) had progressed to PACG; two of seven with appositional and six of 21 with synechial closure. All were advised laser peripheral iridotomy (LPI) in 1995; one of the nine who underwent LPI progressed compared to seven of 19 who refused LPI. Four of those originally diagnosed with appositional closure developed peripheral anterior synechiae. One eye of a person previously diagnosed with appositional PAC was reclassified as a primary angle closure suspect (PACS). There was no significant difference in biometric parameters between those who progressed and those who did not. None developed acute PACG or blindness due to glaucoma.

CONCLUSION

In this population-based study of primary angle closure, the 5-year incidence of PACG was eight patients (28.5%; 95% CI 12-45%). We were unable to identify any features that predicted progression.

Anterior chamber depth in plateau iris syndrome and pupillary block as measured by ultrasound biomicroscopy

PURPOSE

To quantitatively analyze the anterior chamber depth (ACD) in patients with pupillary block and plateau iris syndrome.

DESIGN

Retrospective, consecutive, observational case series.

METHODS

We measured the ACD in 318 eyes of 318 patients who had been diagnosed by ultrasound biomicroscopy as having either pupillary block or plateau iris syndrome. Pupillary block patients were all preiridotomy and plateau iris patients were all postiridotomy. Anterior chamber depth was measured axially from the internal corneal surface to the lens surface using the ultrasound instrument's internal measuring capability.

RESULTS

The mean ACD in patients with plateau iris syndrome (n = 181) was significantly smaller than the hypothesized normal ACD (2.04 +/- 0.30 mm vs 3.0 mm, P =.0001). The mean ACD in patients with pupillary block (n = 137) was also significantly smaller than the hypothesized normal ACD (2.17 +/- 0.30 mm vs 3.0 mm, P =.0001). The mean ACD in patients with plateau iris syndrome was significantly smaller than the ACD in patients with pupillary block (2.04 +/- 0.30 mm vs 2.17 +/- 0.30 mm, P =.001).

CONCLUSIONS

Review of the literature suggests that patients with plateau iris have a normal or deeper axial ACD compared with pupillary block. This study found that the ACD associated with plateau iris syndrome is shallower than normal and also shallower than in pupillary block.

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 microm (AOD500) from the scleral spur, trabecular-iris angle (TIA), iris thickness 500 microm 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 microm; P < 0.001), by both measurement methods used (ACD x ACD and ACD x ACD2). Anterior chamber angle significantly increased, by approximately 50% of the initial value, by the three measurement methods used: AOD250 (P <or= 0.002), AOD500 (P < 0.001), and TIA (P <or= 0.003). The ISA increased by approximately 10 degrees (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 microm and widening its angle by approximately 10 degrees. These findings may be of clinical significance in eyes with angle-closure glaucoma or with occludable angles.

Anterior chamber angle measurement with Anterior Eye Segment analysis system Nidek EAS-1000: improving the repeatability

Previous studies have reported good intraobserver and interobserver repeatability of anterior chamber angle (ACA) assessment using the Anterior Eye Segment analysis system, EAS-1000. This study investigated the influence of fixation pattern, corneal plotting method and camera position on ACA measurements. A Nidek EAS-1000 system was employed for image acquisition and analysis, to obtain measurements of ACA. Twenty-five young healthy subjects participated. The ACAs were different in different quadrants and using different corneal plotting methods (Repeated measures 3-way anova, p < 0.05). However, the difference was <5 degrees and therefore not clinically significant. Alignment along the visual axis or optical axis did not yield any significant difference. Repeatability was improved by asking the subjects to fixate at the flashing light-emitting diode (LED). Temporal and nasal angles also demonstrated better repeatability than vertical angles. In measuring the vertical angles, the camera can be set at either the temporal or nasal side (Paired t-test, p > 0.05). The Anterior Eye Segment analysis system has good clinical repeatability in measuring ACA. It can be further improved with the use of the flashing LED during image acquisition.

Effects of 0.005% latanoprost on ocular anterior structures and ciliary body thickness

PURPOSE

To assess the effects of 0.005% latanoprost on the anterior segment geometry and ciliary body thickness using ultrasound biomicroscopy. Intraocular pressure, refraction, visual acuity, and pupil size were also evaluated.

PATIENTS AND METHODS

Thirty patients with untreated ocular hypertension or primary open-angle glaucoma (mean age: 59.3 +/- 9.9 years) were recruited into this prospective, controlled, open trial. Before and after 1 week of 0.005% latanoprost administration, the following parameters were tested: refraction, visual acuity, pupil diameter, intraocular pressure, 5 conventional ultrasonographic A-scan variables, 16 ultrasound biomicroscopy parameters, and the ultrasound biomicroscopy ciliary body thicknesses at a distance of 1500 microns (CBT1), 2000 microns (CBT2), and 2500 microns (CBT3) from the scleral spur.

RESULTS

Latanoprost 0.005% caused a marked intraocular pressure-lowering effect in all patients (from 22.8 +/- 3.1 mm Hg to 14.1 +/- 2.9 mmHg; -38%, P < 0.0001), without any refractive, visual acuity, or pupillary alterations. The A-scan echobiometry variables were unchanged, while ultrasound biomicroscopy confirmed a significant posttreatment increase of CBT2 (from 434 +/- 140 microns to 536 +/- 127 microns; +102 microns, P = 0.01) and CBT3 (from 319 +/- 103 microns to 412 +/- 100 microns; +93 microns, P = 0.003) compared with controls (CBT2: from 493 +/- 165 microns to 473 +/- 135 microns, -20 microns, P = NS; CBT3: from 388 +/- 130 microns to 365 +/- 87 microns, -23 microns, P = NS). None of the changes observed in the other UBM parameters was statistically significant. No significant correlation was detected between ciliary body thickness increase and intraocular pressure-lowering effect.

CONCLUSION

The increase of ciliary body thickness, which was measured in vivo by ultrasound biomicroscopy and associated with the intraocular pressure-lowering effect, indirectly supports the mechanism of uveoscleral outflow enhancement induced by latanoprost. These data are in agreement with the biochemical hypothesis of the passage of the aqueous flow through the extracellular spaces of the ciliary muscle.

A prospective ultrasound biomicroscopy evaluation of changes in anterior segment morphology after laser iridotomy in Asian eyes

PURPOSE

To prospectively quantify changes in anterior segment morphology after laser iridotomy using gonioscopy and ultrasound biomicroscopy (UBM).

DESIGN

Prospective comparative observational case series.

PARTICIPANTS

Fifty-five fellow eyes of patients presenting with acute primary angle closure (APAC).

METHODS

The fellow eyes of patients presenting with APAC were examined with UBM, A-scan ultrasonography, and optical pachymetry at presentation and 2 weeks after sequential argon/neodymium yttrium-aluminum-garnet laser peripheral iridotomy (LPI). UBM images were analyzed using UBM Pro 2000 software. Baseline measurements were made both under standard lighting conditions and in darkness to look for changes in anterior segment findings.

MAIN OUTCOME MEASURES

The degree of angle opening was measured using the angle-opening distance (AOD) at 250 and 500 microm from the scleral spur (AOD250 and AOD500, respectively) and angle recess area (ARA).

RESULTS

Fifty-five Asian patients were examined; AOD250, AOD500, and ARA all significantly increased after sequential laser iridotomy (P < 0.002). Gonioscopic grading of the angle opening significantly increased in all 4 quadrants (P < 0.001). The Van Herick grade of limbal anterior chamber depth increased (P < 0.001), whereas the number of eyes classified as occludable decreased (73%-33%, P < 0.001). Anterior chamber depth did not change significantly (2.41 mm +/- 0.28 mm vs. 2.42 mm +/- 0.30 mm, P = 0.43) as measured with optical pachymetry. Increased illumination increased the angle-opening measures, but induced a different alteration in peripheral iris morphology. Illumination-induced changes were greater after iridotomy than before laser treatment.

CONCLUSIONS

In Asian eyes at high risk of developing APAC, sequential LPI produced a significant widening of the anterior chamber angle without deepening the anterior chamber centrally. LPI produces changes in iris morphology that are different from those caused by an increase in illumination, indicating that different mechanisms account for angle opening under these 2 conditions.

Age, gender, biometry, refractive error, and the anterior chamber angle among Alaskan Eskimos

BACKGROUND

The prevalence of angle-closure glaucoma (ACG) is greater for Eskimos/Inuit than it is for any other ethnic group in the world. Although it has been suggested that this prevalence may be due to a population tendency toward shallower anterior chamber angles, available evidence for other populations such as Chinese with high rates of ACG has not consistently demonstrated such a tendency.

METHODS

A reticule, slit-lamp, and standard Goldmann one-mirror goniolens were used to make measurements in the anterior chamber (AC) angle according to a previously reported protocol for biometric gonioscopy (BG) (Ophthalmology 1999;106:2161-7). Measurements were made in all four quadrants of one eye among 133 phakic Alaskan Eskimos aged 40 years and older. Automatic refraction, dilated examination of the anterior segment and optic nerve, and A-scan measurements of AC depth, lens thickness, and axial length were also carried out for all subjects.

RESULTS

Both central and peripheral AC measurements for the Eskimo subjects were significantly lower than those previously reported by us for Chinese, blacks, and whites under the identical protocol. Eskimos also seemed to have somewhat more hyperopia. There were no differences in biometric measurements between men and women in this Eskimo population. Angle measurements by BG seemed to decline more rapidly over life among Eskimos and Chinese than blacks or whites. Although there was a significant apparent decrease in AC depth, increase in lens thickness, and increase in hyperopia with age among Eskimos, all of these trends seemed to reverse in the seventh decade and beyond.

CONCLUSIONS

Eskimos do seem to have shallower ACs than do other racial groups. Measurements of the AC angle seem to decline more rapidly over life among Eskimos than among blacks or whites, a phenomenon also observed by us among Chinese, another group with high ACG prevalence. This apparent more rapid decline may be due to a cohort effect with higher prevalence of myopia and resulting wider angles among younger Eskimos and Chinese.

An ultrasound biomicroscopic study of the anterior segment in Indian eyes with primary angle-closure glaucoma

PURPOSE

To evaluate the presence of plateau iris in eyes with primary angle-closure glaucoma (PACG) after laser peripheral iridotomy by gonioscopy and ultrasound biomicroscopy and to evaluate the pathogenesis of this condition by comparing the UBM parameters of these eyes with those in normal subjects.

PATIENTS AND METHODS

This prospective study was carried out in the Glaucoma clinic of a tertiary eye care center. A detailed clinical examination including applanation tonometry, indentation gonioscopy with a Sussman four-mirror gonioscope, and ultrasound biomicroscopic examination in one randomly selected eye of 55 patients (55 eyes) with PACG who had undergone laser peripheral iridotomy and 22 normal subjects (22 eyes).

RESULTS

Among the PACG eyes, 40% (22/55) had an open angle (angle opening distance > 130 microns) and 60% (33/55) eyes had a narrow angle (angle opening distance <or= 130 microns). A large anteriorly placed ciliary process with a narrow ciliary sulcus was found in 9 of the 22 eyes with open angle (40.9%), and 22 of the 33 eyes with narrow angles (66.66%). Trabecular ciliary process distance was significantly larger in the eyes with open angles compared with those with narrow angles ( = 0.001).

CONCLUSIONS

Plateau iris was common in the clinic population studied. Anteriorly directed ciliary processes were seen both in eyes with plateau iris as well as in eyes with PACG that had deep anterior chambers after iridotomy.

Intra-observer and inter-observer repeatability of anterior eye segment analysis system (EAS-1000) in anterior chamber configuration

BACKGROUND

Anterior chamber configuration can be assessed via optical or ultrasonic techniques. Scheimpflug photography is a non-invasive method measuring the anterior segment. The Anterior Eye Segment analysis system, EAS-1000, utilises the Scheimpflug principle and was found to have good repeatability. Previous repeatability studies, however, have had limitations in their design. The current study investigated the intra-observer and interobserver repeatability of the EAS-1000.

METHODS

Twenty-five healthy young subjects were recruited. The anterior chamber angles in different quadrants were measured by two examiners for interobserver analysis. The first examiner repeated the measurement at another session for intra-observer analysis. The 95% limits of agreement and intra-class correlation coefficient (ICC) were calculated. The anterior chamber depth was also measured and compared with ultrasound biometry.

RESULTS

The anterior chamber angle assessment demonstrated good intra-observer (ICC ranging from 0.77 to 0.90 for different quadrants) and interobserver (ICC ranging from 0.68 to 0.81 for different quadrants) repeatability. The 95% intra-observer limits of agreement were within +/-5 degrees. The 95% interobserver limits of agreement were within +/-6 degrees. There was no significant difference between male and female subjects or among angles at different quadrants. The anterior chamber depth was found to be repeatable (ICC > 0.90) with 95% limits of agreement +/-0.1 mm. The anterior chamber depth was shallower than that obtained from ultrasound biometry.

CONCLUSIONS

The EAS-100 is a non-invasive instrument which is repeatable for measuring the anterior chamber angle and depth. It provides quick results and is good for screening purposes. There is an under-estimation of anterior chamber depth, as previously reported.

Modeling passive mechanical interaction between aqueous humor and iris

Certain forms of glaucoma are associated with displacement of the iris from its normal contour. We present here a mathematical model of the coupled aqueous humor-iris system that accountsfor the contribution of aqueous humor flow and passive iris deformability to the iris contour. The aqueous humor is modeled as a Newtonian fluid, and the iris is modeled as a linear elastic solid. The resulting coupled equation set is solved by the finite element method with mesh motion in response to iris displacement accomplished by tracking a pseudo-solid overlying the aqueous humor. The model is used to predict the iris contour in healthy and diseased eyes. The results compare favorably with clinical observations, supporting the hypothesis that passive iris deformation can produce the iris contours observed using ultrasound biomicroscopy.

Effect of cataract surgery on intraocular pressure control in glaucoma patients

PURPOSE

To examine the effect of cataract surgery on intraocular pressure (IOP) control in eyes with angle-closure glaucoma (ACG) and open-angle glaucoma (OAG).

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

METHODS

This study included 74 eyes with ACG and 68 eyes with OAG having cataract surgery. The IOP was measured and the number of glaucoma medications recorded preoperatively, 1 month postoperatively, and then every 3 months. The IOP control in the 2 groups was compared using survival analysis, with failure criteria being an IOP greater than 21 mm Hg, addition of medications, or the need for additional glaucoma surgery.

RESULTS

The mean IOP and number of medications decreased significantly after surgery in both groups (P <.0001). However, the mean decrease in IOP and percentage of IOP reduction in the ACG group were greater than in the OAG group, and fewer medications were required in the ACG group. The cumulative survival probability of IOP control at 24 months was 91.9% in the ACG group and 72.1% in the OAG group. The survival curve in the ACG group was significantly better than in the OAG group (P =.0012). The IOP was controlled without medication in 30 eyes (40.5%) in the ACG group and 13 (19.1%) in the OAG group; the difference between groups was significant (P =.0055).

CONCLUSIONS

Cataract surgery substantially reduced IOP and the number of medications required for IOP control in glaucomatous eyes. Specifically, cataract extraction normalized the IOP in most eyes with ACG.

Ultrasound biomicroscopy of the aging rhesus monkey ciliary region

Ultrasound biomicroscopy of the living rhesus monkey ocular ciliary region was undertaken to identify age-dependent changes that might relate to the progression of presbyopia. Monkeys were anesthetized and pharmacologically cyclopleged, the eyelids were held open with a lid speculum, and sutures were placed beneath the medial and lateral rectus muscles. Ultrasound biomicroscopy imaging of the nasal and temporal quadrants of the eye were performed, and the live images were recorded to videotape. Subsequent image analysis was performed to obtain objective morphometric measurements of the ciliary body region. The ciliary body inner radius of curvature, outer radius of curvature, inner arc length, area, thickness, perimeter, zonular fiber length, and circumlental space were measured. Zonular space was calculated. The circumlental space decreased with increasing age in the temporal quadrant. The other morphologic measurements were not significantly correlated with age or body weight. Most morphologic measurements were significantly different comparing temporal vs. nasal quadrants. Bifurcation of the posterior zonular fibers was frequently observed. Although temporal circumlental space was the only measurement found to change with age, ultrasound biomicroscopy of the living rhesus ciliary region did identify distinct nasal vs. temporal asymmetries, which may reflect anatomical requirements for convergence-associated accommodation.

Ocular parameters in the subgroups of angle closure glaucoma

PURPOSE

This study was conducted to compare anatomical parameters, thought to be responsible for causing angle closure glaucoma (ACG), among eyes having acute, subacute or chronic ACG.

METHODS

Ninety consecutive patients diagnosed with a subgroup of ACG, and 30 age, sex and refraction matched controls, provided a total of 240 eyes for a prospective study. The refractive error, corneal diameter, keratometry, pachymetry, lens thickness and axial length were measured and the relative lens position was calculated. The data were analysed by paired t-test, ANOVA, signed rank test and multivariate analysis.

RESULTS

Acute ACG eyes were mildly hyperopic. All the ACG subgroups had similarly short eyeballs and a steeper corneal curvature compared to control eyes. Acute ACG lenses were thicker than all the other groups (P < 0.001), but all ACG eyes had thicker lenses than the controls. Corneal diameters and anterior chamber depths were decreased in acute and chronic ACG eyes compared with subacute ACG and controls (P < 0.001). The uninvolved fellow eyes in each subgroup differed from affected eyes only in having more posteriorly positioned lenses.

CONCLUSIONS

There was a spectrum of anatomical variations seen in the subgroups of ACG. Acute ACG eyes expressed an extreme shift of anatomical features away from normal, especially, smaller corneal diameters, leading to a large mobile lens in an already crowded anterior segment. This predisposed them to a severe relative pupillary block, and to a form of ciliary block glaucoma. Chronic ACG eyes were less divergent from normal and therefore could have suffered a milder form of the same kind of angle closure, but over a more prolonged period. Subacute ACG eyes deviated least from controls, and therefore exhibited mild signs and spontaneous resolution. Further work is required to elucidate completely the pathophysiology that leads to ACG.

Changes in anterior chamber angle width and depth after intraocular lens implantation in eyes with glaucoma

OBJECTIVE

To examine the changes in anterior chamber angle width and depth induced by intraocular lens (IOL) implantation in eyes with angle-closure glaucoma (ACG), in eyes with open-angle glaucoma (OAG), and in eyes with no evidence of glaucoma or ocular hypertension.

DESIGN

A comparative, nonrandomized, interventional study.

PARTICIPANTS

Seventy-seven eyes with ACG, 73 eyes with OAG, and 74 control eyes undergoing cataract extraction and IOL implantation.

INTERVENTION

All eyes underwent phacoemulsification and soft acrylic IOL implantation.

MAIN OUTCOME MEASURES

The angle width and depth of the anterior chamber were measured using a Scheimpflug videophotography system before surgery, and at 1 week and at 1, 3, 6, 9, and 12 months after surgery.

RESULTS

Before surgery, the mean anterior chamber angle width and depth in the ACG group was less than that in either the OAG or control groups by approximately 10 degrees in angle width and 1.0 mm in depth (P < 0.0001). After cataract extraction and IOL implantation, the angle width and depth increased significantly in all three groups (P < 0.0001). Although the width and depth in the ACG group were still smaller than that in the other groups, the differences decreased to 2 degrees for angle width and 0.3 mm for depth. In addition, no significant differences were found in these values between the OAG and control groups before or after surgery. Furthermore, no significant changes were observed in the angle width or depth in any of the three groups throughout the postoperative observation period. As expected, the mean preoperative intraocular pressure (IOP) in the ACG and OAG groups was higher than that in the control group. After cataract surgery, however, the mean IOP decreased significantly and was almost the same in all three groups at 1, 6, and 12 months after surgery.

CONCLUSIONS

The width and depth of the anterior chamber angle in eyes with ACG increased significantly after cataract extraction and IOL implantation and became similar to that in eyes with OAG and that in normal eyes, which may lead to the decrease in IOP seen in the postoperative period. No significant changes were observed in angle width and depth in any of the three groups after surgery.

Quantitative assessment of the anterior segment using ultrasound biomicroscopy

The development of ocular imaging devices has progressed rapidly during the past 10 years. Ultrasound biomicroscopy has revolutionized the evaluation of the anterior segment of the eye. The qualitative information gathered using this technology has contributed to our understanding of the pathophysiology of angle-closure glaucoma, pigmentary glaucoma, and a variety of other anterior segment disorders. However, the area of quantitative analysis of ultrasound biomicroscopic images remains largely to be developed. This review describes the role of ultrasound biomicroscopy in the measurement of the anatomic structures and their configurations within the anterior segment. Included are previously published and established methods as well as methods in their early stages of development. Application of quantitative image analysis techniques should yield significant information about mechanisms of appositional angle closure, dynamic functions of the iris, accommodation, and presbyopia.

Ultrasound biomicroscopic study of ciliary body thickness in eyes with narrow angles

PURPOSE

To determine the ciliary body thickness and other biometric findings in eyes with narrow angles.

METHODS

Eighteen otherwise normal eyes with narrow angles in 18 Japanese patients and 18 normal control eyes with open angles in 18 age-matched and sex-matched Japanese patients were studied. A-scan ultrasonography was performed to measure anterior chamber depth, lens thickness, axial length, and relative lens position. Ultrasound biomicroscopy was also performed to obtain measurements of the anterior ocular structures, including anterior chamber depth and ciliary body thickness at sites 1 mm and 2 mm posterior to the scleral spur (positions 1 and 2, respectively).

RESULTS

Compared with normal control eyes, the narrow-angle eyes showed a shallower anterior chamber (narrow angle, 1.87 +/- 0.27 mm; control, 2.69 +/- 0.26 mm; P <.0001), a thicker lens (4.97 +/- 0.49 mm, 4.26 +/- 0.53 mm; P <.0001), a more anteriorly located lens (2. 21 +/- 0.13, 2.35 +/- 0.14; P <.0001), a shorter axial length (22.70 +/- 0.97 mm, 23.41 +/- 0.86 mm; P =.012), and a thinner ciliary body (position 1: 454 +/- 107 microm, 602 +/- 86 microm; P <.0001; position 2: 203 +/- 50 microm, 321 +/- 68 microm; P <.0001). Lens thickness was significantly correlated with ciliary body thickness at positions 1 (R(2) = 0.34; P =.0001) and 2 (R(2) = 0.43; P <.0001). Anterior chamber depth was significantly correlated with ciliary body thickness at positions 1 (R(2) = 0.48; P <.0001) and 2 (R(2) = 0.56; P <.0001).

CONCLUSION

Thinning of the ciliary body may be one of the important factors associated with the anterior location of the lens, the increased lens thickness, and the decreased anterior chamber depth in eyes with a narrow angle.

Intraocular lens tilt and decentration after implantation in eyes with glaucoma

PURPOSE

To evaluate the extent of intraocular lens (IOL) tilt and decentration after implantation in eyes with glaucoma.

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

METHODS

Fifty-two eyes of 52 patients with glaucoma and 52 control eyes from 52 age-matched patients had phacoemulsification with IOL implantation. Twenty-nine eyes had closed-angle glaucoma (CAG), and the other 23 eyes had open-angle glaucoma (OAG). The extent of IOL tilt and decentration was measured using Scheimpflug videophotography 1 week and 1, 3, 6, 9, and 12 months postoperatively.

RESULTS

The mean tilt angle in the glaucoma group was significantly greater than in the control group throughout the follow-up. Mean decentration length was also greater in the glaucoma than in the control group, but the difference was not significant. The incidence of eyes showing a marked tilt (greater than 5 degrees) or decentration (greater than 0.5 mm) was higher in the glaucoma than in the control group. The mean tilt angle and the incidence of eyes showing a marked tilt or decentration in the CAG group were significantly greater than in the control group.

CONCLUSION

Intraocular lens tilt was more extensive in the eyes with glaucoma, especially in those with CAG, than in normal eyes. Decentration was also greater in the glaucoma groups than in the control group, although the differences were not significant.

Plateau iris syndrome: changes in angle opening associated with dark, light, and pilocarpine administration

PURPOSE

To report changes in angle configuration associated with dark, light, and pilocarpine administration in plateau iris syndrome.

METHOD

In 10 eyes of 10 patients with plateau iris syndrome and persistent narrow angles after patent peripheral Nd:YAG laser iridotomy, ultrasound biomicroscopy was used to image variations in angle opening, iris thickness, and trabecular-ciliary process distance. Measurements were taken in the dark, in full room light, and after administration of pilocarpine 2%.

RESULTS

Average angle opening distance increased in the light compared with the dark (113+/-34 microm vs. 22+/-34 microm, P = .0001) and increased further after pilocarpine administration (171+/-52 microm vs. 113+/-34 microm, P = .0034). Average iris thickness decreased in the light compared with the dark (338+/-34 microm vs. 436+/-58 microm, P = .0009) and decreased further after pilocarpine administration (253+/-48 microm vs. 338+/-34 microm, P = .0002). Average trabecular meshwork-ciliary process distance measurements were smaller than normal and did not change significantly in the light compared with the dark (481+/-42 microm vs. 464+/-44 microm, P = .4001) or after pilocarpine administration compared with light (451+/-67 microm vs. 481+/-42 microm, P = .1304).

CONCLUSIONS

In plateau iris syndrome, anteriorly located ciliary processes support the peripheral iris. Changes in angle opening in dark and light are solely related to changes in iris thickness. Pilocarpine produces iris thinning and is an effective method of opening the angle. Ultrasound biomicroscopy can be used to perform a darkroom provocative test, which provides information on whether the angle anatomically closes in the dark.