Effect of Shear Stress on Attachment of Corneal Endothelial Cells in Association With Corneal Endothelial Cell Loss After Laser Iridotomy

A computational fluid dynamics investigation of endothelial cell damage from glaucoma drainage devices

Glaucoma drainage devices (GDDs) are prosthetic-treatment devices for treating primary open-angle glaucoma. Despite their effectiveness in reducing intraocular pressures (IOP), endothelial cell damage (ECD) is a commonly known side-effect. There have been different hypotheses regarding the reasons for ECD with one being an induced increase in shear on the corneal wall. A computational fluid dynamics (CFD) model was used to investigate this hypothesis in silico. The Ahmed Glaucoma Valve (AGV) was selected as the subject of this study using an idealised 3D model of the anterior chamber with insertion angles and positions that are commonly used in clinical practice. It was found that a tube-cornea distance of 1.27 mm or greater does not result in a wall shear stress (WSS) above the limit where ECD could occur. Similarly, a tube-cornea angle of 45° or more was shown to be preferable. It was also found that the ECD region has an irregular shape, and the aqueous humour flow fluctuates at certain insertion angles and positions. This study shows that pathological amounts of WSS may occur as a result of certain GDD placements. Hence, it is imperative to consider the associated fluid force interactions when performing the GDD insertion procedure.

Unraveling the mechanobiology of cornea: From bench side to the clinic

The cornea is a transparent, dome-shaped structure on the front part of the eye that serves as a major optic element and a protector from the external environment. Recent evidence shows aberrant alterations of the corneal mechano-environment in development and progression of various corneal diseases. It is, thus, critical to understand how corneal cells sense and respond to mechanical signals in physiological and pathological conditions. In this review, we summarize the corneal mechano-environment and discuss the impact of these mechanical cues on cellular functions from the bench side (in a laboratory research setting). From a clinical perspective, we comprehensively review the mechanical changes of corneal tissue in several cornea-related diseases, including keratoconus, myopia, and keratectasia, following refractive surgery. The findings from the bench side and clinic underscore the involvement of mechanical cues in corneal disorders, which may open a new avenue for development of novel therapeutic strategies by targeting corneal mechanics.

The Response of Corneal Endothelial Cells to Shear Stress in an In Vitro Flow Model

Purpose

Corneal endothelial cells are usually exposed to shear stress caused by the aqueous humour, which is similar to the exposure of vascular endothelial cells to shear stress caused by blood flow. However, the effect of fluid shear stress on corneal endothelial cells is still poorly understood. The purpose of this study was to explore whether the shear stress that results from the aqueous humour influences corneal endothelial cells.

Methods

An in vitro model was established to generate fluid flow on cells, and the effect of fluid flow on corneal endothelial cells after exposure to two levels of shear stress for different durations was investigated. The mRNA and protein expression of corneal endothelium-related markers in rabbit corneal endothelial cells was evaluated by real-time PCR and western blotting.

Results

The expression of the corneal endothelium-related markers ZO-1, N-cadherin, and Na⁺-K⁺-ATPase in rabbit corneal endothelial cells (RCECs) was upregulated at both the mRNA and protein levels after exposure to shear stress.

Conclusion

This study demonstrates that RCECs respond favourably to fluid shear stress, which may contribute to the maintenance of corneal endothelial cell function. Furthermore, this study also provides a theoretical foundation for further investigating the response of human corneal endothelial cells to the shear stress caused by the aqueous humour.

Aqueous humor dynamics in human eye: A lattice Boltzmann study

This paper presents a lattice Boltzmann model to simulate the aqueous humor (AH) dynamics in the human eye by involving incompressible Navier-Stokes flow, heat convection and diffusion, and Darcy seepage flow. Verifying simulations indicate that the model is stable, convergent and robust. Further investigations were carried out, including the effects of heat convection and buoyancy, AH production rate, permeability of trabecular meshwork, viscosity of AH and anterior chamber angle on intraocular pressure (IOP). The heat convection and diffusion can significantly affect the flow patterns in the healthy eye, and the IOP can be controlled by increasing the anterior chamber angle or decreasing the secretion rate, the drainage resistance and viscosity of AH. However, the IOP is insensitive to the viscosity of AH, which may be one of the causes that the viscosity would not have been considered as a factor for controlling the IOP. It's interesting that all these factors have more significant influences on the IOP in pathologic eye than healthy one. The temperature difference and the eye-orientation have obvious influence on the cornea and iris wall shear stresses. The present model and simulation results are expected to provide an alternative tool and theoretical reference for the study of AH dynamics.

Iridocorneal contact as a potential cause of corneal decompensation following laser peripheral iridotomy

PURPOSE

This study aimed to investigate the relationship between corneal decompensation following laser peripheral iridotomy (LPI) and iridocorneal endothelial contact.

STUDY DESIGN

Retrospective observational case series.

METHODS

Specular microscopy images of LPI recipients with narrow angles were taken at the central cornea and the 8 midperipheral corneal regions at approximately 3 mm from the center. Eleven eyes of 11 patients had a minimum of  ≤ 1600 cells/mm² among 8 midperipheral corneal endothelial cell densities (ECDs). Radial scans of the angles in the 8 directions were taken with ultrasound biomicroscopy (UBM) in the supine and face-down positions. The minimum and maximum angle opening distance at 750 μm from the scleral spur of the 8 directions were defined as the narrowest and widest angles, respectively. The ECD of the narrowest angle direction was compared with the ECD of the widest angle direction.

RESULTS

When UBM was performed with the subject in the supine position, the iris and cornea at the narrowest angle were in contact in only 4 of 11 eyes, while in the face-down position, the iris and the cornea at the narrowest angle were in contact in 10 of the 11 eyes. In the face-down UBM, the midperipheral ECD of the narrowest angle direction was significantly smaller than the midperipheral ECD of the widest angle direction (P = 0.006).

CONCLUSION

The ECD of the narrow angle direction can decrease after LPI. This suggests that corneal endothelial cell damage following LPI may be due to mechanical damage from iridocorneal endothelial contact.

A Rare Case of Acute Bilateral Endothelial Decompensation after Prophylactic Nd:YAG Laser Iridotomy Requiring Endothelial Keratoplasty

Aim

To describe a case of acute bilateral endothelial decompensation following prophylactic Nd:YAG laser iridotomy (LI) for occludable angles.

Background

Although regarded safe, LI can occasionally be a source of various ocular complications, including corneal endothelial damage. In the herein case, we describe the first case of acute bilateral endothelial decompensation after Nd:YAG LI.

Case description

A 63-year-old man was referred for consultation due to visual acuity deterioration in both eyes 2 weeks after undergoing an uneventful prophylactic LI for occludable angles. On examination, bilateral corneal edema with Descemet's membrane folds was observed. Direct corneal damage from the laser beam was not seen. Specular microscopy failed to count endothelial density. Anterior-segment optical coherence tomography (OCT), ultrasound biomicroscopy, and ocular biometry were performed. The patient was referred for bilateral endothelial keratoplasty.

Conclusion

Subacute endothelial dysfunction should be considered as a possible adverse event following Nd:YAG LI and patients should be advised accordingly.

Clinical relevance

Surgeons should be aware of the potentially devastating complication of bilateral corneal decompensation following routine Nd:YAG LI, even in patients without preexisting corneal injury. Patients should be advised accordingly.

How to cite this article

Weill Y, Abulafia A, Smadja D, et al. A Rare Case of Acute Bilateral Endothelial Decompensation after Prophylactic Nd:YAG Laser Iridotomy Requiring Endothelial Keratoplasty. J Curr Glaucoma Pract 2020;14(3):109–111.

Numerical model to predict and compare the hypotensive efficacy and safety of minimally invasive glaucoma surgery devices

Purpose

To predict and compare the hypotensive efficacy of three minimally-invasive glaucoma surgery (MIGS) implants through a numerical model.

Methods

Post-implant hypotensive efficacy was evaluated by using a numerical model and a computational fluid dynamics simulation. Three different devices were compared: the XEN 45 stent (tube diameter, 45 μm), the XEN 63 stent (63 μm) and the PreserFlo microshunt (70 μm). The influence of the filtration bleb pressure (Bp) and tube diameter, length, and position within the anterior chamber (AC) on intraocular pressure (IOP) were evaluated.

Results

Using baseline IOPs of 25, 30 and 50 mmHg, respectively, the corresponding computed post-implant IOPs for each device were as follows: XEN 45: 17 mmHg (29% decrease), 19 mmHg (45%) and 20 mmHg (59%) respectively; XEN 63: 13 mmHg (48%), 13 mmHg (62%), and 13 mmHg (73%); PreserFlo: 12 mmHg (59%), 13 mmHg (73%) and 13 mmHg (73%). At a baseline IOP of 35 mmHg with an increase in the outflow resistance within the Bp from 5 to 17 mmHg, the hypotensive efficacy for each device was reduced as follows: XEN45: 54% to 37%; XEN 63: 74% to 46%; and PreserFlo: 75% to 47%. The length and the position of the tube in the AC had only a minimal (non-significant) effect on IOP (<0.1 mmHg).

Conclusions

This hydrodynamic/numerical model showed that implant diameter and bleb pressure are the two most pertinent determinants of hypotensive efficacy. In distinction, tube length and position in the AC do not significantly influence IOP.

Computational Study on the Biomechanics of Pupil Block Phenomenon

Pupil blocking force (PBF) can indicate the potential risk of pupil block (PB), which is considered as a main pathogenic factor of primary angle-closure glaucoma (PACG). However, the effect of PB on the PBF under different pupil diameters and iris-lens channel (ILC) distance was unknown. Besides, a simple and practical method to assess PBF has not been reported yet. In this study, 21 finite element models of eyes with various pupil diameters (2.4 mm–2.6 mm) and ILC (2 μm–20 μm) were constructed and were conducted to simulate aqueous humor flow by fluid-solid coupling numerical simulation. PBF in each model was calculated based on the numerical simulation results and was fitted using response surface methodology. The results demonstrated that ILC distance had a more significant effect than pupil diameter on PBF. With the decrease of ILC distance, the PBF increased exponentially. When the reduced distance was lower than 5 μm, the PBF exploded quickly, resulting in a high risk of iris bomb. The PBF also varied with pupil diameter, especially under the condition of narrow ILC. Both ILC distance and pupil diameter could explain more than 97% variation in PBF, and a second-order empirical model has been developed to be a good predictor of PBF. Based on the linear relationship between anterior chamber deformation and PBF, a threshold value of PBF was given to guide clinical decisions. This study could be used to investigate PACG pathological correlation and its pathogenesis, so as to provide a reference value for clinical diagnosis of PACG.

Mesenchymal cells and fluid flow stimulation synergistically regulate the kinetics of corneal epithelial cells at the air-liquid interface

PURPOSE

In vivo microenvironments are critical to tissue homeostasis and wound healing, and the cornea is regulated by a specific microenvironment complex that consists of cell-cell interactions, air-liquid interfaces, and fluid flow stimulation. In this study, we aimed to clarify the effects of and the correlations among these three component factors on the cell kinetics of corneal epithelial cells.

METHODS

Human corneal epithelial-transformed (HCE-T) cells were cocultured with either primary rat corneal fibroblasts or NIH 3T3 fibroblasts. We employed a double-dish culture method to create an air-liquid interface and a gyratory shaker to create fluid flow stimulation. Morphometric and protein expression analyses were performed for the HCE-T cells.

RESULTS

Both the primary rat fibroblasts and the NIH 3T3 cells promoted HCE-T cell proliferation, and the presence of fluid flow synergistically enhanced this effect and inhibited the apoptosis of HCE-T cells. Moreover, fluid flow enhanced the emergence of myofibroblasts when cocultured with primary rat fibroblasts or NIH 3T3 cells. Extracellular signal-regulated kinase and p38 signaling were regulated either synergistically or independently by both fluid flow and cellular interaction between the HCE-T and NIH 3T3 cells.

CONCLUSION

The cell-cell interaction and fluid flow stimulation in the air-liquid interface synergistically or independently regulated the behavior of HCE-T cells. Fluid flow accelerated the phenotypic change from corneal fibroblasts and NIH 3T3 cells to myofibroblasts. Elucidation of the multicomponent interplay in this microenvironment will be critical to the homeostasis and regeneration of the cornea and other ocular tissues.

Aqueous humour flow in the posterior chamber of the eye and its modifications due to pupillary block and iridotomy

The anterior chamber (AC) and posterior chamber (PC) of the eye are connected through the pupil and are filled with aqueous humour. The aqueous flows from the posterior to the AC at an approximately constant rate, and the intraocular pressure is governed by this rate and the resistance to aqueous outflow. In some patients the iris and lens come into contact, leading to pressure build-up in the PC, peripheral axial shallowing of the AC and, possibly, to angle-closure glaucoma. This can lead to blindness, which may be prevented by surgically creating an iridotomy, that is a hole through the iris to facilitate the flow from the posterior to the AC. The problem of optimal size and location of an iridotomy is still poorly understood. In this article, we study aqueous flow in the PC and investigate how it is modified in the presence of an iridotomy. Our approach is based on the lubrication theory, which allows us to solve the problem semi-analytically. We treat the iridotomy as a point sink and assume that the flux through it is proportional to the pressure. We find that the ideal size and location of an iridotomy are influenced by various geometrical and fluid mechanical factors, the most relevant of which are the size of the hole and the length and height of the iris-lens channel. For certain iridotomy diameters, we find that the jet velocity through the iridotomy might be large enough to cause possible corneal damage.

Computational simulation of aqueous humour dynamics in the presence of a posterior-chamber versus iris-fixed phakic intraocular lens

Purpose

To compare aqueous humour (AH) dynamics in the presence of a precrystalline (Implantable Collamer Lens^®; ICL) or iris-fixed (Artiflex^®) phakic intraocular lens (PIOL).

Methods

By computational fluid dynamics simulation, AH flow was modelled through a peripheral iridotomy (PI) or central lens hole (both 360 μm) in the presence of an Artiflex or ICL lens, respectively. The impacts of AH flow were then determined in terms of wall shear stress (WSS) produced on the endothelium or crystalline lens. Effects were also modelled for different scenarios of pupil diameter (PD 3.5 or 5.5 mm), ICL vault (100, 350, 800 μm) and number of Artiflex iridotomies (1 or 2) and location (12 or 6 o’clock).

Results

For a PD of 3.5 mm, AH volumes flowing from the posterior to the anterior chamber were 37.6% of total flow through the lens hole (ICL) and 84.2% through PI (Artiflex). For an enlarged PD (5.5 mm), corresponding values were 10.3% and 81.9% respectively, so PI constitutes a very efficient way of evacuating AH. Central endothelial WSS in Pa was lower for the large vault ICL and the Artiflex (1⁻⁰³ and 1.1⁻⁰³ respectively) compared to the PIOL-free eye (1.6⁻⁰³). Crystalline lens WSS was highest for the lowest vault ICL (1⁻⁰⁴).

Conclusions

AH flow varied according to the presence of a precrystalline or iris-fixed intraocular lens. Endothelial WSS was lower for an implanted ICL with large vault and Artiflex than in the PIOL-free eye, while highest crystalline WSS was recorded for the lowest vault ICL.

Endothelial cell loss and graft survival after penetrating keratoplasty for laser iridotomy-induced bullous keratopathy

PURPOSE

To assess corneal endothelial cell loss after penetrating keratoplasty (PK) treatment for laser iridotomy (LI)-induced bullous keratopathy (BK).

METHODS

A retrospective study conducted on consecutive patients who underwent PK between March 2000 and December 2011. Patients who had undergone more than 24 months of follow-up were included. Patients who underwent PK were subcategorized into two groups based on their diagnosis of BK prior to PK; PK was performed to treat either LI-BK or non LI-BK. The cell density of the central corneal endothelium and the graft survival were evaluated during follow-up.

RESULTS

Corneal endothelial cell density decreased in a similar fashion in both the LI-BK and non LI-BK patients, though the cell density decreased significantly faster in the LI-BK group than in the non LI-BK group throughout the 108 months of the study (p = 0.026). The mean cell loss at 36 months for the LI-BK group was 57.7% vs. 63.2% for the non LI-BK, 76.9% vs. 70.1% at 72 months, and 85.6% vs. 72.0% at 108 months. No eye among 21 eyes in the LI-BK group (0%) had failed grafts, whereas 4 of 25 eyes in the non LI-BK group (16.0%) had failed grafts at 60 months (p = 0.114).

CONCLUSIONS

The outcome of PK for BK secondary to LI was no worse than the outcome of PK for other types of BK. However, our long-term follow-up after PK showed that cell density decreased faster in the LI-BK group than in the non LI-BK, suggesting that cell loss might be involved in the existence of LI prior to PK.

Three-year outcome of Descemet stripping automated endothelial keratoplasty for bullous keratopathy after argon laser iridotomy

PURPOSE

The aim of this study was to evaluate the 3-year outcome of Descemet stripping automated endothelial keratoplasty (DSAEK) for the treatment of bullous keratopathy secondary to argon laser iridotomy (ALI).

METHODS

A total of 22 consecutive patients (22 eyes) with ALI who underwent DSAEK were retrospectively analyzed. Best spectacle-corrected visual acuity (BSCVA), endothelial cell density, and complications were investigated over 3 years postoperatively. The outcome of DSAEK was also compared between the ALI group and 21 other patients with Fuchs endothelial dystrophy (FED) or pseudophakic bullous keratopathy (PBK) (FED/PBK group).

RESULTS

The median BSCVA improved from logarithm of the minimum angle of resolution 1.40 before DSAEK to 0.30 at 6 months, 0.30 at 12 months, 0.22 at 24 months, and 0.15 at 36 months after surgery. The median endothelial cell loss was 20.3% at 6 months, 18.4% at 12 months, 32.5% at 24 months, and 46.5% at 36 months. Comparison of the ALI group with the FED/PBK group showed no significant difference in the BSCVA or endothelial cell density. Rejection affected 9.1% of the ALI group versus 0% of the FED/PBK group (P = 0.49), the graft dislocation rate was 0% versus 9.5% (P = 0.23), and posterior synechiae were found in 31.8% versus 4.8% (P = 0.046).

CONCLUSIONS

The 3-year outcome of DSAEK for bullous keratopathy after ALI was excellent. However, caution should be exercised in patients with a history of ALI to avoid posterior synechiae after DSAEK.

Laser iridotomy and the corneal endothelium: a systemic review

This study aims to systemically review the effect of laser iridotomy on the corneal endothelium. Searches were performed for studies that either compared corneal endothelial cell density/count, corneal thickness and morphology pre- and postiridotomy, or evaluated the postiridotomy development of corneal decompensation. There were 26 eligible studies. Our review shows that the effect of laser iridotomy on the corneal endothelium has been investigated with varying results. Although it has been demonstrated to be a relatively safe procedure, there is still the potential long-term risk of corneal decompensation, for which a corneal transplantation may be indicated eventually. The longest interval between laser iridotomy and corneal decompensation reported was 8 years. Mechanisms proposed for endothelial damage include direct focal injury, thermal damage, mechanical shock waves, iris pigment dispersion, transient rise in intraocular pressure, inflammation, turbulent aqueous flow, time-dependent shear stress on endothelium, chronic breakdown of blood-aqueous barrier and damage from bubbles that settled onto the endothelium. Inherent risk factors identified were iridotrabecular contact, current or prior acute angle closure, pigmented irides, small iris-to-endothelium distance, pre-existing endothelial disease and diabetes. Intervention-related risk factors include laser type, delivery and quantity. The significance of the risk factors and their direct association with the development of corneal decompensation remain to be determined. Understanding these risk factors may allow physicians to counsel their patients better. They may offer opportunities for preventive strategies, allowing us to ensure that a procedure performed to prevent disease progression and visual loss does not cause further morbidity.

Physiology of aqueous humor dynamic in the anterior chamber due to rapid eye movement

The nature of aqueous humor (AH) mixing in the anterior chamber (AC) of the human eye due to rapid eye movement (REM) has not been fully understood and has been somewhat a controversial issue. This study uses a computational modeling approach to shed light on this issue. For this purpose a numerical method was developed and used to solve the mathematical equations governing the flow and mixing of aqueous humor motion in the eye subjected to such movements. Based on the experimental measurements available in the literature for the average and maximum amplitudes of the eye movements, a harmonic model for the REM was developed. The corresponding instantaneous and time-averaged velocity fields were evaluated. The simulation results showed that, contrary to earlier reports, the REM led to complex flow structures and a 3-D mixing of AH in the anterior chamber. In addition, the mixing velocity increased in direct proportion to the REM amplitudes. Thus, the AC flow generated by REM could carry nutrients to the posterior surface of the cornea during the sleep. Furthermore, the shear stress acting on the corneal endothelial cells due to REM was computed and compared with that of buoyancy driven flow in the AC due to temperature gradient. It was found that the shear stress generated by REM is much higher than that introduced by the natural convection. A video file for providing a better understanding of the AH mixing process in the AC was also prepared. This video is available on the web.

Investigation of Saccadic Eye Movement Effects on the Fluid Dynamic in the Anterior Chamber

The aqueous humor (AH) flow in the anterior chamber (AC) due to saccadic movements is investigated in this research. The continuity, Navier-Stokes and energy equations in 3D and unsteady forms are solved numerically and the saccadic motion was modeled by the dynamic mesh technique. Firstly, the numerical model was validated for the saccadic movement of a spherical cavity with analytic solutions and experimental data where excellent agreement was observed. Then, two types of periodic and realistic saccadic motions of the AC are simulated, whereby the flow field is computed for various saccade amplitudes and the results are reported for different times. The results show that the acting shear stress on the corneal endothelial cells from AH due to saccadic movements is much higher than that due to normal AH flow by buoyancy induced due to temperature gradient. This shear stress is higher on the central region of the cornea. The results also depict that eye saccade imposes a 3D complicated flow field in the AC consist of various vortex structures. Finally, the enchantment of heat transfer in the AC by AH mixing as a result of saccadic motion is investigated.

Visualization of irrigation fluid flow and calculation of its velocity distribution in the anterior chamber by particle image velocimetry

PURPOSE

To visualize irrigation fluid flow and calculate its velocity distribution in the anterior chamber during phacoemulsification by particle image velocimetry.

METHODS

Porcine eyes were fixed in a glass chamber filled with balanced salt solution. An ultrasound handpiece was fixed to the glass chamber, and its tip was inserted into the anterior chamber through a corneal incision. Irrigation fluid was mixed with fluorescein-labeled liposomes as tracer particles. During phacoemulsification without ultrasound, a sheet-like Nd-YAG pulsed laser beam was emitted and moved from the iris plane to the top of the cornea continuously. Images of illuminated liposomes in the anterior chamber were captured at short intervals with a CCD camera, and the velocity distribution of irrigation fluid flow was calculated by particle image velocimetry.

RESULTS

By particle image velocimetry, the flow velocity distribution could be calculated in any plane of the anterior chamber. Dynamic flow of the irrigation fluid, ejected from the tip of the ultrasound handpiece and returned to an aspiration port, was visualized clearly in the anterior chamber. The maximum flow velocity in the anterior chamber was 342 ± 131 mm/s.

CONCLUSIONS

Particle image velocimetry enabled the visualization of irrigation fluid flow and quantification of its velocity distribution in different planes of the anterior chamber during cataract surgery. These data are essential for evaluating the safety and efficacy of new surgical settings and devices during phacoemulsification.

Surgical outcome of Descemet's stripping automated endothelial keratoplasty for bullous keratopathy secondary to argon laser iridotomy

BACKGROUND: To report the 6-month clinical outcome of Descemet's stripping automated endothelial keratoplasty (DSAEK) for bullous keratopathy (BK) secondary to argon laser iridotomy (ALI), and compare the results with those of DSAEK for pseudophakic bullous keratopathy (PBK) or Fuchs' endothelial dystrophy (FED). METHODS: A total of 103 patients (54 with ALI, 28 with PBK, 21 with FED) undergoing DSAEK were retrospectively analyzed. Simultaneous cataract surgery was performed in 37 patients with ALI and 13 with FED. Preoperative ocular conditions, best spectacle-corrected visual acuity (BSCVA), spherical equivalent refraction (SE), induced astigmatism, keratometric value, endothelial cell density (ECD), and complications were determined over 6 months postoperatively. RESULTS: Mean axial length in the ALI group (21.8 ± 0.8 mm) was significantly shorter than that in the FED (P = 0.02) or PBK groups (P = 0.003). Severe corneal stromal edema (n = 6), advanced cataract (n = 10), posterior synechia (n = 3), poor mydriasis (n = 5), and Zinn zonule weakness (n = 1) were found only in the ALI group. A significant improvement was observed in postoperative BSCVA in all groups. No significant difference was observed in BSCVA, SE, induced astigmatism, keratometric value, ECD, or complications among the three groups. CONCLUSIONS: Descemet's stripping automated endothelial keratoplasty for BK secondary to ALI showed rapid postoperative visual improvement, with similar efficacy and safety to that observed in DSAEK for PBK or FED.

Non-Descemet stripping automated endothelial keratoplasty for endothelial dysfunction secondary to argon laser iridotomy

PURPOSE

To report clinical outcomes of non-Descemet stripping automated endothelial keratoplasty (nDSAEK) as treatment of endothelial dysfunction secondary to argon laser iridotomy (ALI).

DESIGN

Single-center, prospective, noncomparative, interventional case series.

METHODS

Six eyes of six patients (two men, four women; mean age, 74.5 years) with bullous keratopathies secondary to ALI were treated with endothelial keratoplasty without recipient Descemet stripping. The donor endothelial lamella was inserted using a pull-through technique using a Busin glide with intraocular lens glide (i.e., Kobayashi double-glide technique). Best-corrected visual acuity (BCVA), astigmatism, and donor central endothelial cell density (ECD) were recorded before surgery and at six months after surgery. Intraoperative and postoperative complications also were recorded. Main outcome measures were preoperative and postoperative central ECD, with calculation of cell loss rate. BCVA, induced astigmatism, and complications also were evaluated.

RESULTS

All patients reached more than 20/32 BCVA, with two (33.3%) reaching 20/20. Mean induced astigmatism in measurable cases was 0.85 +/- 0.49 diopters. The average and standard deviation ECD at six months were 2390.5 +/- 522.4 cells/mm(2) (range, 1589 to 2898 cells/mm(2)), representing a mean cell loss from preoperative donor cell measurements of 25.8% +/- 14.7%. Complications included one case of donor dislocation requiring rebubbling (16.7%) and one case of subclinical endothelial rejection (16.7%).

CONCLUSIONS

This modified endothelial keratoplasty technique (nDSAEK and double-glide technique) for treatment of endothelial dysfunction secondary to ALI produced excellent clinical outcomes such as reduced endothelial cell loss, good visual acuity, and minimal induced astigmatism.