Anterior Chamber Anatomy Research Articles

Non-Descemet stripping endothelial keratoplasty for bullous keratopathy in patients with atopic dermatitis: A long-term case report.

Patients with atopic dermatitis undergoing penetrating keratoplasty (PKP) face a high risk of postoperative complications. Endothelial keratoplasty may be a safer alternative for such patients, including those with abnormal anterior chamber anatomy. 3 male patients, aged 33 to 44, presented with blurred vision at Keio University Hospital. Bullous keratopathy was diagnosed through slit-lamp examination and specular microscopy. Two patients had well-controlled systemic atopic dermatitis, while 1 had blepharitis associated with atopic dermatitis. Two patients had peripheral anterior synechia, and 2 had undergone glaucoma surgery before keratoplasty. Non-Descemet stripping endothelial keratoplasty (nDSAEK) was performed by a single surgeon. The best-corrected visual acuity ranged from 0.7 to 1.5 logMAR before surgery and from 0.2 to 2.3 logMAR after surgery. One year post-surgery, the graft remained clear in 2 cases; however, in the case of repeated glaucoma surgeries after nDSAEK, the graft became edematous. Corneal endothelial cell density was 1586 and 1988 cells/mm² in 2 cases and undetectable in the failed case. The follow-up period ranged from 2.5 to 9 years. Despite the presence of peripheral anterior synechia or prior glaucoma surgery, some patients experienced a favorable long-term postoperative course following nDSAEK. This procedure may offer a safer alternative for treating patients with atopic dermatitis who have ocular complications that present a high risk for PKP.

Morphometric analysis of the anterior chamber in patients with refractory glaucoma after micropulse cyclophotocoagulation

PURPOSE. To evaluate the anatomical-topographic parameters of the anterior chamber of the eye before and after micropulse cyclophotocoagulation (mCPC) in patients with refractory glaucoma in pseudophakic and phakic eyes.METHODS. The study included 60 patients (62 eyes) with moderate (7 eyes) and advanced (55 eyes) refractory glaucoma. Study groups were formed as follows: the 1st group consisted of 31 pseudophakic eyes (32 patients), the 2nd group included 31 phakic eyes (30 patients). All patients underwent mCPC according to a modified technique. To assess anatomical parameters patients underwent optical coherence tomography of the anterior segment (AS-OCT). Anterior chamber angle (ACA) and anterior chamber depth (ACD) were measured at specific follow-up time points after mCPC.RESULTS. Hypotensive effect by the end of 12-month follow-up was achieved in the patients of the first group in 83.1% of cases, in the second group — in 80.6% of cases (p<0.05). According to OCT findings, anterior chamber depth in patients with phakic eyes during the 12-month follow-up remained the same as before surgery — 2.43±0.21 (mm). In the other group with pseudophakic eyes, anterior chamber depth also did not change during the observation period, with an average value of 3.27±0.12 (mm). No significant changes (p>0.05) were found in the irido-corneal angle measurements in the 4 meridians over the entire follow-up period in both groups.CONCLUSION. Micropulse cyclophotocoagulation performed at fluence rate F=121 J/cm2 does not result in changes of structures of the anterior segment of the eye. The stability of anterior chamber anatomy as well as the absence of postoperative complications in early and longterm follow-up proved the minimal traumatic effect of this surgery in patients with refractory glaucoma.

Influence of anterior chamber depth and vault on anterior chamber angle morphology after phakic posterior chamber intraocular lens implantation.

This study aims to investigate the influence of anterior chamber depth (ACD) and vault on the anterior chamber angle (ACA) morphology in myopic individuals implanted with posterior chamber phakic intraocular lenses. This retrospective case series involved 231 eyes receiving a 13.2-mm implantable collamer lens (ICL). Preoperative anterior chamber anatomy was assessed using anterior segment optical coherence tomography (AS-OCT) and optical tomography, while postoperative evaluation employed AS-OCT. ACA morphology was characterized pre- and postoperatively through trabecular iris angle (TIA750), ACA distance opening (AOD750) and trabecular iris space area (TISA750). The influence of ACD and vault was examined by categorizing the sample into ACD (shallow, average and deep) and vault (low, optimal and high) groups. Preoperative ACA morphology varied based on ACD, with shallower ACDs exhibiting narrower TIA750, smaller AOD750 and TISA750. ICL implantation induced greater ACA narrowing more in the deep ACD group (TIA750 = 20.1 degrees; AOD750 = 0.82mm and TISA750 = 0.44mm2) compared to the shallow ACD group (TIA750 = 15.2 degrees; AOD750 = 0.44mm and TISA750 = 0.21mm2). Postoperatively, deeper ACDs showed larger ACAs. Increasing vault magnitude led to increased ACA narrowing, with the low vault group exhibiting smaller closure (TIA750 = 14.3degrees; AOD750 = 0.56mm and TISA750 = 0.29mm2) compared to the high vault group (TIA750 = 20.8degrees; AOD750 = 0.73mm and TISA750 = 0.36mm2). The magnitude of ACA narrowing associated with the vault had a consistent effect across different ACD groups. Posterior chamber intraocular lens implantation results in ACA narrowing, the extent of which is contingent upon preoperative anterior chamber and ACA morphology, with additional influence from vault magnitude.

Chamber shallowing technique for challenging DMEK cases: Tucking cellulose spears under the speculum to augment posterior pressure.

Some anterior chambers do not readily shallow because of insufficient posterior pressure and/or very deep anterior chamber anatomy, which can make unscrolling descemet membrane endothelial keratoplasty (DMEK) tissue more challenging with an unmodified tap technique. We present a hands-free method for augmenting posterior pressure by temporarily tucking cellulose sponges under the blades of the eyelid speculum. The sponges transfer some of the eyelid speculum's weight onto the bulbar surface posterior to the iris, thereby indenting the sclera and causing the iris diaphragm to bulge further forward. This hands-free technique can transform a potentially challenging DMEK case into a more straightforward one by facilitating both a shallow anterior chamber and a bimanual unscrolling technique. However, it only works in bicameral eyes with a vitreous body (e.g., an eye with penetrating keratoplasty, vitreous syneresis, and axial myopia) and will not work in unicameral eyes after vitrectomy (e.g., an eye with an Anterior Chamber Intraocular Lens (ACIOL)).

Effect of anatomical differences and intraocular lens design on negative dysphotopsia.

To assess the effect of ocular anatomy and intraocular lens (IOL) design on negative dysphotopsia (ND). Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands. Ray-tracing study based on clinical data. Ray-tracing simulations were performed to assess the effect of anatomical differences and differences in IOL design on the peripheral retinal illumination. To that end, eye models that incorporate clinically measured anatomical differences between eyes of patients with ND and eyes of pseudophakic controls were created. The anatomical differences included pupil size, pupil centration, and iris tilt. The simulations were performed with different IOL designs, including a simple biconvex IOL design and a more complex clinical IOL design with a convex-concave anterior surface. Both IOL designs were analyzed using a clear edge and a frosted edge. As ND is generally considered to be caused by a discontinuity in peripheral retinal illumination, this illumination profile was determined for each eye model and the severity of the discontinuity was compared between eye models. The peripheral retinal illumination consistently showed a more severe discontinuity in illumination with ND-specific anatomy. This difference was the least pronounced, 8%, with the frosted edge clinical IOL and the most pronounced, 18%, with the clear edge biconvex IOL. These results show that small differences in the ocular anatomy or IOL design affect the peripheral retinal illumination. Therewith, they can increase the severity of ND by up to 18%.

Surgeons preferences in descemet membrane endothelial keratoplasty (DMEK).

To explore the attitudes, preferences, and barriers of DMEK among corneal specialists in Saudi Arabia. An anonymous survey was sent through an online platform to members of the Saudi Ophthalmological Society. The survey was designed to capture data covering: demographic data, practice patterns of keratoplasty techniques, DMEK technique preferences, barriers, and facilitators to performing DMEK. Thirty-five (33% response rate) surgeons participated in the questionnaire. Sixty-eight percent were in practice for less than or equal to 10years. Thirteen surgeons were performing DMEK. Participating in any training capacity was observed among surgeons who performed DMEK (92%). The main selection criteria for this procedure were patients with normal anterior chamber anatomy (77%). The main barrier against DMEK adoption among surgeons who do not perform the procedure was the lack of experience (91%). Strategies to help begin performing DMEK were eye banks support (prepared grafts, backup tissue for inadvertent loss), access to wet-lab training courses, and higher surgical volume. DMEK is not highly performed among corneal specialists in Saudi Arabia; however, there is evident interest in adopting this technique. Strategies toward filling the gap of lacking experience would facilitate the adoption of the procedure. Eye banks play a crucial role by providing prepared tissues, which would lessen part of the technical difficulty.

Diurnal Changes in Accommodation Amplitude and Anterior Segment Parameters During Ramadan Fasting

Background: The purpose of this research was to investigate the diurnal effect of Ramadan fasting on the amplitude of accommodation and anterior segment parameters in visually healthy participants.Materials and Methods: The study included 68 healthy individuals, aged 26–42 years. The subjective accommodation amplitude was measured using the "minus lens" technique. Corneal refraction (K1, K2, and Kmax), central corneal thickness, corneal volume, anterior chamber volume, and anterior chamber depth parameters were evaluated using the Scheimpflug camera system. Participants were evaluated twice, at 08:00 and 16:00, while fasting during Ramadan. Data were analyzed by paired sample t-test.Results: The mean age of the participants, of which 28 were women and 40 were men, was 34.38±4.93 (range: 26–42). Comparison of measurements taken at 08:00 and 16:00 during fasting showed that at 16:00, the K1 values (08:00: 42.81±1.51 diopter and 16:00: 42.85±1.50 diopter, P = 0.016) and Kmax values (08:00: 44.29 ± 1.73 diopter and 16:00: 44.38±1.78 diopter, P = 0.020) were significantly steeper. When data collected at 08.00 and 16.00 were compared, there were no significant differences in diurnal changes: amplitude of accommodation (08:00: 7.39±1.40 diopter and 16:00: 7.37±1.40 diopter, P = 0.783), central corneal thickness (08:00: 535.60 ± 30.43 µm and 16:00: 535.25±30.66 µm, P = 0.694), corneal volume (08:00: 59.72±3.85 mm3 and 16:00: 59.60±3.98 mm3, P= 0.344), anterior chamber volume (08.00: 170.91±30.77 mm3 and 16.00: 171.22±32.61 mm3, P = 0.808) and anterior chamber depth (08:00: 2.91 ± 0.28 mm and 16:00: 2.92 ± 0.29 mm, P = 0.053).Conclusions: The results showed that dehydration due to fasting affects some anterior segment parameters, such as corneal refraction; however, it does not affect the diurnal changes of amplitude of accommodation, corneal pachymetry, or anterior chamber anatomy.

Implantation of ArtificialIris, a CustomFlex® iris prosthesis, in a trauma patient with an Artisan lens

Purpose: To evaluate probable complications of ArtificialIris implantation with iris-fixated intraocular lens.
 Method: Development of photophobia, glare, and psychological strain during face-to-face communication in a 23-year-old man with a widespread traumatic iris defect terminate to make a decision for performing implantation an ArtificialIris (HumanOptics, Erlangen, Germany) under the remnant iris without removing the patient’s existing Artisan lens.
 Results: Without any intraoperative or postoperative complications, the patient’s visual acuity increased by one line, the endothelial cell loss was comparable with the cell loss associated with standard cataract surgery, and the anterior chamber depth and anterior chamber anatomy did not change. At the final follow-up examination, the mean intraocular pressure (IOP) did not differ from baseline, and we achieved high level of patient satisfaction and subjective vision improvement. We discuss the particular importance of considering the patient’s expectations, the appropriate measurements, ways to perfect color evaluation, and the types of ArtificialIris products.
 Conclusion: The implantation of the ArtificialIris in patients with aphakic iris-supported lenses (i.e., preexisting Artisan lenses) is a feasible approach and a useful option for patients with thin irises and iris hypoplasia who are at risk of subluxation or the dislocation of the PCIOL as well as those with sclerally fixed PCIOLs.

Gas-Graft Coverage After DMEK: A Clinically Validated Numeric Study.

PurposeWe investigate the influence of positioning, gas fill, and anterior chamber size on bubble configuration and graft coverage after Descemet's membrane endothelial keratoplasty (DMEK).MethodsWe use a mathematical model to study the bubble shape and graft coverage in eyes of varying anterior chamber depths (ACD). The governing equations are solved numericly using the open source software OpenFOAM. Numeric results are validated clinically so that clinical gas fill measures can be correlated with numeric results providing gas-graft coverage information otherwise clinically inaccessible.ResultsIn a phakic eye (ACD = 2.65 mm) with a gas fill of 35%, graft contact ranged from 35% to 38% depending on positioning and increased to 85% to 92% with a 70% fill. In contrast, positioning of a pseudophakic eye (ACD = 4.35) with a gas fill of 35% results in graft contact ranging from 8% to 52%, increasing to 63% to 94% with a 70% fill. The mathematical model demonstrates negligible differences between air and SF6 results and interestingly, a very thin central patch of aqueous humor within the gas bubble is found in some cases.ConclusionsGraft coverage in phakic eyes (ACD ≤ 3 mm) is dominated by the gas fill and less sensitive to patient positioning. In pseudophakic eyes with larger values of ACD, the graft coverage depends on gas fill and patient positioning with positioning even more important as ACD increases.Translational RelevanceAnterior chamber depth markedly influences the role of patient positioning in gas-filled eyes after DMEK due to the interplay between anterior chamber anatomy and gas bubble morphology.

Effects of sustained daily latanoprost application on anterior chamber anatomy and physiology in mice

Latanoprost is a common glaucoma medication. Here, we study longitudinal effects of sustained latanoprost treatment on intraocular pressure (IOP) in C57BL/6J mice, as well as two potential side-effects, changes in iris pigmentation and central corneal thickness (CCT). Male C57BL/6J mice were treated daily for 16 weeks with latanoprost. Control mice were treated on the same schedule with the preservative used with latanoprost, benzalkonium chloride (BAK), or handled, without ocular treatments. IOP and CCT were studied at pre-treatment, 2 “early” time points, and 2 “late” time points; slit-lamp analysis performed at a late time point; and expression of corneal and iridial candidate genes analyzed at the end of the experiment. Latanoprost lowered IOP short, but not long-term. Sustained application of BAK consistently resulted in significant corneal thinning, whereas sustained treatment with latanoprost resulted in smaller and less consistent changes. Neither treatment affected iris pigmentation, corneal matrix metalloprotease expression or iridial pigment-related genes expression. In summary, latanoprost initially lowered IOP in C57BL/6J mice, but became less effective with sustained treatment, likely due to physiological adaptation. These results identify a new resource for studying changes in responsiveness associated with long-term treatment with latanoprost and highlight detrimental effects of commonly used preservative BAK.

Transpupillary Nd:YAG Laser Cystotomy for Iris Pigment Epithelial Cysts with Secondary Progressive Angle Closure

Two patients were diagnosed as having unilateral iris pigment epithelial (IPE) cysts that were documented to enlarge and induce angle closure. Transpupillary IPE cystotomies were performed using the Nd:YAG laser as a prophylactic measure to prevent angle-closure glaucoma. Anterior chamber anatomy and cyst dimensions were assessed before, during, and after long-term follow-up using slit-lamp biomicroscopy, gonioscopy, and 20- or 35-MHz high-frequency ultrasound imaging. Cystotomy resulted in immediate, visible deflation of both IPE cysts with subsequent resolution of angle closure. The cyst contents appeared clear and no secondary inflammation or glaucoma occurred. No evidence of cyst recurrence has been noted during 3 and 8 years of follow-up, respectively. Transpupillary Nd:YAG laser cystotomy offered a minimally invasive and effective treatment for angle closure induced by progressive IPE cysts.

Optimal fast T2‐weighted magnetic resonance microscopy imaging of the eye and its clinical application

To compare a half-Fourier single-shot rapid acquisition with relaxation enhancement (RARE) sequence with a balanced steady-state free precession (b-SSFP) sequence in the evaluation of the eye using magnetic resonance (MR) microscopy imaging and to clarify the usefulness of RARE microscopy imaging in evaluating nonoperative glaucoma patients and patients who have undergone surgery for glaucoma or cataract. One-mm and 2-mm slice thickness images of RARE sequence and b-SSFP sequence using a 1.5 T MR unit and a 23-mm microscopy coil were obtained in eight healthy volunteers. The signal-to-noise (S/N) ratio of aqueous humor in the anterior chamber was measured quantitatively and visualization of the anterior chamber anatomy was assessed qualitatively. Furthermore, we evaluated 21 glaucoma patients (including six postoperative patients) and four patients after cataract surgery with 2-mm slice thickness RARE MRI. The 2-mm slice thickness RARE imaging had a significantly greater S/N ratio than the 1-mm slice thickness RARE imaging (P < 0.05) and acquired the best image quality among the four types of images (P < 0.01). Additionally, 2-mm slice thickness RARE microscopy imaging could depict anterior chamber anatomy of glaucoma eyes and eyes after cataract surgery. We believe that optimal fast T2-weighted MR microimaging might become a useful ophthalmologic examination technique.

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 biomicroscopy of the rat eye: effects of cholinergic and anticholinergic agents

Over the past few years the rat has gained prominence as an animal model for the study of glaucoma. However, no systematic study of the angle structures and the effects of medications on angle anatomy in the rat has been reported to date. We investigated the normal rat anterior segment anatomy in vivo using ultrasound biomicroscopy (UBM) and determined the effect of both cholinergic and anticholinergic medications on angle structures. Fourteen eyes of seven 2-month-old female Wistar rats were imaged using an ultrasound biomicroscope and a modified eyecup. Baseline measurements of the anterior chamber depth (ACD), trabecular-iris angle (TIA), iris thickness at the thickest point near the pupillary margin (IT), angle-opening distance (AOD) (distance between the posterior corneal surface and anterior iris surface measured at 200 microm from the scleral spur), corneal thickness (CT) and irido-zonular distance (IZD) were obtained. Imaging was repeated 30 min after instillation of one drop of cyclopentolate 1% and 48 h later 30 min after pilocarpine 1% instillation. The same measurements were obtained and compared to baseline values. Baseline values for all parameters recorded were not significantly different among contralateral eyes. After instillation of either pilocarpine or cyclopentolate, ACD was the only parameter that did not change significantly from baseline. In contrast, TIA, AOD, IZD, and IT were significantly different among the three groups. Post-hoc analysis (Bonferroni test) revealed differences among all three groups of eyes for TIA and AOD. A difference was also found between the pilocarpine-treated group and the other two groups for IZD and IT. A very small difference detected between the pilocarpine-treated group and the baseline measurements for CT was caused by the zero variance of measurements in the former group. Although both pilocarpine and cyclopentolate induced angle narrowing, inspection of the ultrasonic images revealed a differential effect. Pilocarpine caused a "pupillary block-like" picture, while cyclopentolate caused crowding of the iris base in the angle. Baseline characteristics of the normal rat anterior chamber anatomy were established. Both cyclopentolate and pilocarpine cause angle narrowing in the rat eye, by different mechanisms.

Vitrectomy for Pars Plana Placement of a Glaucoma Seton

Trabeculectomy, even with supplemental antifibrosis agents, has a low success rate in controlling intraocular pressure (IOP) in certain cases; ones involving severe anterior-chamber-angle disease are particularly challenging. Ten patients with advanced, non-neovascular glaucoma underwent vitrectomy and pars plana placement of seton implants. The tube was placed through the pars plana sclerotomy in each case because severe anterior chamber angle narrowing, aphakia, or penetrating keratoplasty prevented standard placement. Previous trabeculectomy had failed to control IOP in 9 of the 10 patients. In each, the preoperative IOP was 25 mm Hg or more despite maximal medical therapy. In nine of the patients, the postoperative IOP was 19 mm Hg or less, without pressure-lowering agents. The seton appeared to be functional in all of the cases. Vision remained stable or improved in seven cases, but deteriorated in three due to graft failure, progressive traction retinal detachment, or rhegmatogenous retinal detachment (one case each). Pars plana placement of tubes for glaucoma seton implants should be considered as an alternative to anterior chamber placement in certain cases of refractory glaucoma in which the anterior chamber anatomy has been severely disrupted.

Response of Argon Laser Trabeculoplasty With Varying Anterior Chamber Anatomy

We studied one randomly selected eye of 50 consecutive primary open-angle glaucoma patients treated with argon laser trabeculoplasty to assess response differences as functions of anterior chamber anatomy and refraction. We found no significant differences related to these variables, and thus conclude that argon laser trabeculoplasty may be performed successfully in patients with crowded angles as long as the trabecular meshwork can be visualized.

Slit Lamp Reformation of the Anterior Chamber Following Trabeculectomy

Out of 50 consecutive trabeculectomies performed over a 10-month period, 13 flat or shallow anterior chambers were reformed immediately following surgery a total of 19 times without complication at the slit lamp, using hyaluronic acid. Three months after surgery, there was no significant difference between the reformed and nonreformed eyes in terms of intraocular pressure or visual acuity change. We conclude that reformation at the slit lamp using hyaluronic acid is a safe, effective means of restoring anterior chamber anatomy following trabeculectomy.