A Comparison of the Corneal Thickness Following Descemet's Stripping Automated Endothelial Keratoplasty and Descemet's Membrane Endothelial Keratoplasty.

PURPOSE: To compare the central corneal thickness before and after Descemet's stripping automated endothelial keratoplasty (DSAEK) and Descemet's membrane endothelial keratoplasty (DMEK), and to evaluate the recipient corneal thickness following DSAEK. METHODS: The corneal thickness was compared between two groups of eyes following DMEK and DSAEK, performed by a single surgeon between 2015 and 2017. We evaluated the recipient corneal thickness and central corneal thickness pre- and postoperatively at 1, 3, and 6 months using anterior segment optical coherence tomography. Recipient corneal thickness was defined as the corneal thickness without graft thickness. RESULTS: We included DMEK and DSAEK eyes (n = 26 each), which were similar in terms of their etiologies. Preoperatively, there was no significant difference in the central corneal thickness between the groups (DSAEK, median [interquartile range]: 721 [606.5 to 847.8] µm; and DMEK: 690 [618 to 722.3] µm; p = 0.30). Despite the tendency of the central corneal thickness to be significantly greater (p < .01) at 6 months following DSAEK (619.5 [607.8 to 661.3] µm) compared with that following DMEK (497.5 [475.8 to 525.3] µm), there was no significant difference at 6 months between the recipient corneal thickness following DSAEK (488.5 [443.8 to 515] µm) and central corneal thickness following DMEK (p = 0.54). CONCLUSIONS: DSAEK eyes display a similar tendency of stromal thinning as DMEK eyes.

Optical characteristics after Descemet membrane endothelial keratoplasty: 1-year results.

PURPOSE: To evaluate the corneal characteristics after Descemet membrane endothelial keratoplasty (DMEK) compared with normal corneas. METHODS: Patients who underwent DMEK at Yokohama Minami Kyosai Hospital were included and prospectively evaluated pre-operatively and at postoperative months 1, 3, 6, and 12, and compared to healthy controls. Corneal characteristics evaluated included corneal curvature (keratometric value [KV]; D), central corneal thickness (CCT), peripheral corneal thickness (PCT), and corneal higher-order aberrations [HOAs] at 6.0 mm diameter, calculated by anterior segment optical coherence tomography and logarithm of the minimal angle of resolution [logMAR]. RESULTS: A total of 30 eyes of 30 patients (6 men, 24 women, mean age 73.4 ± 7.4 years) were included and compared with 31 age-matched healthy control eyes (13 men, 18 women; mean age 73.0 ± 6.7 years). LogMAR after DMEK improved from 0.87 ± 0.07 preoperatively to 0.04 ± 0.07 at 12 months postoperatively (p<0.001). Although anterior KVs of DMEK eyes were similar to those of control eyes, posterior KVs were significantly larger (-6.4 ± 0.3 D vs. -6.3 ± 0.2 D; p = 0.02). Total HOAs after DMEK improved from 1.94 ± 1.05 µm preoperatively to 1.05 ± 0.16 µm at 12 months postoperatively (p<0.001), which was significantly higher than that in control eyes (0.63 ± 0.06) (p<0.001). Despite the similar CCTs in the two groups, the PCT was significantly larger in DMEK eyes (704 ± 41 µm vs 669 ± 38 µm, p = 0.002) at 12 months. CONCLUSION: Despite achieving good visual function and excellent corneal clarity, eyes that underwent DMEK showed a steeper posterior KV and higher corneal HOAs than normal eyes even at 12 months after surgery.

Factors associated with endothelial cell density loss post Descemet membrane endothelial keratoplasty for bullous keratopathy in Asia.

PURPOSE: To investigate the factors associated with endothelial survival after Descemet's membrane endothelial keratoplasty (DMEK) in eyes of Asian patients with bullous keratopathy (BK). METHODS: In this retrospective, consecutive interventional case series, 72 eyes of 72 patients who underwent DMEK were evaluated. Best corrected visual acuity (BCVA) and corneal endothelial cell density (ECD) were assessed at 12 months postoperatively. Multiple regression analysis was performed to assess parameters such as age, sex, axial length, preoperative visual acuity, re-bubbling, the ratio of graft to cornea area, iris damage scores, types of filling gases, air or SF6 volume in the anterior chamber (AC) on postoperative day 1, and ECD loss rates at 12 months postoperatively. RESULTS: BCVA improved significantly at 12 months after DMEK (P < .001). The rate of ECD loss at 12 months after DMEK was 54.4 ± 16.1%. Multiple linear regression analysis showed that a larger ratio of graft to corneal area (P = 0.0061) and higher donor ECD (P = 0.042) were the primary factors for a lower ECD loss rate at 12 months after DMEK. CONCLUSION: A relatively larger graft size compared to the host cornea and more donor ECD might help endothelial survival in patients with BK. Moreover, for such patients, the surgeon should attempt to use a relatively larger graft size when performing DMEK, particularly in Asian eyes.

A Deep Learning Approach in Rebubbling After Descemet's Membrane Endothelial Keratoplasty.

PURPOSE: To evaluate the efficacy of deep learning in judging the need for rebubbling after Descemet's endothelial membrane keratoplasty (DMEK). METHODS: This retrospective study included eyes that underwent rebubbling after DMEK (rebubbling group: RB group) and the same number of eyes that did not require rebubbling (non-RB group), based on medical records. To classify the RB group, randomly selected images from anterior segment optical coherence tomography at postoperative day 5 were evaluated by corneal specialists. The criterion for rebubbling was the condition where graft detachment reached the central 4.0-mm pupil area. We trained nine types of deep neural network structures (VGG16, VGG19, ResNet50, InceptionV3, InceptionResNetV2, Xception, DenseNet121, DenseNet169, and DenseNet201) and built nine models. Using each model, we tested the validation data and evaluated the model. RESULTS: This study included 496 images (31 eyes from 24 patients) in the RB group and 496 images (31 eyes from 29 patients) in the non-RB group. Because 16 picture images were obtained from the same point of each eye, a total of 992 images were obtained. The VGG19 model was found to have the highest area under the receiver operating characteristic curve (AUC) of all models. The AUC, sensitivity, and specificity of the VGG19 model were 0.964, 0.967, and 0.915, respectively, whereas those of the best ensemble model were 0.956, 0.913, and 0.921, respectively. CONCLUSIONS: This automated system that enables the physician to be aware of the requirement of RB might be clinically useful.

Effect of Graft Shift Direction on Graft Detachment and Endothelial Cell Survival After Descemet Membrane Endothelial Keratoplasty.

PURPOSE: To investigate the effects of graft shift orientation on clinical outcomes after Descemet membrane endothelial keratoplasty (DMEK). METHODS: This study used intraoperative video images to retrospectively examine the effect of graft shift direction in 50 eyes of 50 patients. Correlations were assessed between graft shift direction and multiple parameters. RESULTS: The graft detachment rate was higher in eyes with an inferior graft shift than in those without (superior, 0% and 5.0%; nasal, 0% and 20.0%; inferior, 16.7% and 55.0%; temporal, 16.7% and 45.0%; and any segment, 23.3% and 65.0%; for graft shift-negative and graft shift-positive cases, respectively). Postoperative endothelial cell density reduction was higher in eyes with an inferior graft shift (1 month, 23.6% ± 13.7% and 37.5% ± 18.8%; 3 months, 31.6% ± 16.4% and 45.2% ± 15.2%; and 6 months, 39.8% ± 14.9% and 50.7% ± 16.6%; for graft shift-negative and graft shift-positive cases, respectively). Eyes with a superior graft shift had lower postoperative endothelial cell density reduction than those without (1 month, 36.9% ± 16.6% and 20.0% ± 13.1%; 3 months, 45.3% ± 13.3% and 27.4% ± 16.2%; and 6 months, 51.3% ± 14.6% and 35.9% ± 14.5%; for graft shift-negative and graft shift-positive cases, respectively). Graft shift direction did not affect postoperative best-corrected visual acuity or central corneal thickness. CONCLUSIONS: Graft shift direction in DMEK, especially inferior graft shift, affected the postoperative graft detachment rate. Superior graft shift had a beneficial effect on postoperative corneal endothelial values. These data suggest that inferior graft shift should be avoided in DMEK.

Risk Factors for Cystoid Macular Edema After Descemet Membrane Endothelial Keratoplasty.

PURPOSE: To investigate factors associated with cystoid macular edema (CME) after Descemet membrane endothelial keratoplasty (DMEK) in Asian eyes. METHODS: In this retrospective, interventional, consecutive case series, 77 eyes of 65 patients who underwent DMEK were evaluated; in 53 eyes, cataract surgery was performed 1 month before DMEK (staged DMEK), and 24 eyes underwent DMEK alone (simple DMEK). Central retinal thickness, incidence of CME, postoperative best-corrected visual acuity, central corneal thickness, and corneal endothelial cell density were assessed at 1, 3, and 6 months after surgery. Multiple regression analysis and stepwise variable selection were performed for parameters such as type of surgery, iris damage scores, age, sex, axial length, preoperative visual acuity, rebubbling, air volume in the anterior chamber on postoperative day 1, history of diabetes, and endothelial cell density loss rates at 6 months after surgery. RESULTS: CME occurred in 12 (15.6%) of 77 eyes. There was no significant difference in best-corrected visual acuity between eyes with and without CME (P = 0.27). Multivariable analysis revealed that the difference in iris damage scores between before and after DMEK (P < 0.001), air volume in the anterior chamber (P = 0.012), simple DMEK (P = 0.020), and rebubbling (P = 0.036) were significantly associated with CME. Stepwise variable selection indicated that iris damage (P < 0.001) was the most important risk factor for CME. CONCLUSIONS: Iris damage due to DMEK might be a possible risk and aggravating factor for the development of CME after DMEK. Surgeons should attempt to minimize damage to the iris.

Evaluation of Anterior and Posterior Corneal Irregularity After Descemet Membrane Endothelial Keratoplasty.

PURPOSE: To investigate the changes in anterior and posterior corneal irregularity after Descemet membrane endothelial keratoplasty (DMEK). METHODS: This retrospective study included 27 eyes of 23 patients who underwent DMEK and 27 eyes of age-matched healthy controls. Corneal irregularity indexes, surface regularity of height (SR_H), and higher-order aberrations were evaluated in 4- and 6-mm diameters of the cornea, preoperatively and postoperatively, using anterior segment optical coherence tomography. RESULTS: The best spectacle-corrected visual acuity (logarithm of the minimum angle of resolution) improved from 1.01 ± 0.54 preoperatively to 0.08 ± 0.11 at 6 months postoperatively. Anterior SR_H was significantly lower at 6 months postoperatively [from 1.86 ± 0.73 to 1.20 ± 0.34 (P < 0.01) (4-mm) and from 2.29 ± 0.62 to 1.64 ± 0.42 (P < 0.01) (6-mm)]. Posterior SR_H showed a significant decrease from 6.87 ± 4.19 to 2.18 ± 0.51 (4-mm) and from 5.21 ± 2.60 to 2.44 ± 0.38 (6-mm) at 6 months postoperatively (P < 0.001). The SR_H was positively correlated with best spectacle-corrected visual acuity (anterior 4 mm: R = 0.524; anterior 6 mm: R = 0.477; posterior 4 mm: R = 0.655; posterior 6 mm: R = 0.655, P < 0.001) and with higher-order aberrations for 4-mm and 6-mm diameters (R = 0.511 and R = 0.325, P < 0.001, respectively). CONCLUSIONS: The SR_H reflects corneal irregularity and is correlated with the visual outcome after DMEK, which may be very helpful to corneal surgeons as an index indicating the severity before DMEK, and the quality of visual function after DMEK.

Short Axial Length and Iris Damage Are Associated With Iris Posterior Synechiae After Descemet Membrane Endothelial Keratoplasty in Asian Eyes.

PURPOSE: To evaluate the frequency and severity of iris posterior synechiae after Descemet membrane endothelial keratoplasty (DMEK) and to investigate possible causes of iris posterior synechiae. METHODS: Twenty-three eyes were investigated in 20 Asian patients who underwent DMEK 1 month after phacoemulsification and intraocular lens implantation surgery. A preexisting iris damage score was defined by iris damage and classified into 5 grades. Six months after DMEK, the iris posterior synechiae severity score was evaluated based on the extent of posterior synechiae, according to every 45 degrees of the pupillary rim (posterior synechiae score, 0-8). Correlations were analyzed between the posterior synechiae score and preexisting factors (preexisting iris damage score, axial length [AXL], anterior chamber depth, and anterior chamber volume, both before and after cataract surgery). RESULTS: Iris posterior synechiae appeared in 20 of 23 eyes (87.0%). Best spectacle-corrected visual acuity significantly improved at 6 months after DMEK (P < 0.001). Endothelial cell density was 1596 ± 530 cells/mm (P < 0.001); loss of cell density was 37.8 ± 19.9% at 6 months. Single regression analysis showed that the onset of iris posterior synechiae was correlated with the preexisting iris damage score (P = 0.006, r = 0.55), AXL (P < 0.001, r = -0.71), anterior chamber depth (P < 0.001, r = -0.70), and anterior chamber volume before cataract surgery (P < 0.001, r = -0.79). CONCLUSIONS: Iris posterior synechiae after DMEK frequently appeared in Asian eyes with shorter AXLs or a damaged iris.

Descemet membrane endothelial keratoplasty using ophthalmic viscoelastic devices for eyes with laser iridotomy-induced corneal endothelial decompensation: Analysis of 11 eyes.

Graft insertion into the anterior chamber is one of the most important procedures for successful Descemet membrane endothelial keratoplasty (DMEK). Especially in eyes with fragile zonular fibers and a shallow anterior chamber, smooth graft insertion tends to become more difficult. Ophthalmic viscoelastic devices (OVDs) can usually help to retain the space in the anterior chamber and to improve the safety of manipulations during various ophthalmic surgeries. Therefore, we postulated that graft insertion into the anterior chamber could be improved by their use. The purpose of this study is to investigate the availability and efficacy of OVDs during graft insertion in DMEK surgery.A total of 11 eyes of 9 patients with bullous keratopathy who underwent DMEK were retrospectively analyzed. The cause of bullous keratopathy was corneal endothelial decompensation following laser iridotomy in all eyes. We used low viscous dispersive OVD (Opegan) to maintain the anterior chamber depth during graft insertion in all of the eyes.The graft insertion was uneventful in all of the eyes. The inserted graft was attached to the back surface of the cornea. However, 2 eyes needed rebubbling, and after rebubbling, all of the 2 grafts completely attached to the back surface of the cornea. The best spectacle-corrected visual acuity significantly improved 6 months after surgery (P < .001) and the central corneal thickness significantly decreased (P < .001).The use of OVD facilitates safer graft insertion during DMEK, and subsequently prevents endothelial cell loss, which leads to a successful procedure.

Outcomes of Descemet Membrane Endothelial Keratoplasty for Vitrectomized Eyes with Sutured Posterior Chamber Intraocular Lens.

PURPOSE: To evaluate the clinical outcomes of Descemet membrane endothelial keratoplasty (DMEK) for vitrectomized eyes that underwent pars plana vitrectomy (PPV) and transscleral-sutured intraocular lens (IOL) implantation. METHODS: In this retrospective study, DMEK cases were reviewed from medical records and divided into two groups: the eyes after PPV and transscleral-sutured IOL implantation (vitrectomized group) and the eyes with in-the-bag IOL implantation (control group) prior to DMEK. The main outcome measures included time of graft unfolding during surgery and best spectacle-corrected visual acuity (BSCVA), central corneal thickness (CCT), and endothelial cell density (ECD) at 1, 3, and 6 months after the DMEK. RESULTS: Twenty-three eyes (vitrectomized group, n = 8; control group, n = 15) in 23 patients were included in this study. The unfolding time was significantly longer in the vitrectomized group than in the control group (P < 0.001). Postoperative BSCVA was worse in the vitrectomized group (0.16 ± 0.15) than in the control group (-0.06 ± 0.06; P = 0.017). The improvement in BSCVA was negatively correlated with the patients' age and frequency of previous surgeries. CONCLUSIONS: Despite the longer graft unfolding time and limited visual recovery, DMEK should be applicable to vitrectomized eyes with transscleral-sutured IOL implantation.

Modified Descemet's Stripping Automated Endothelial Keratoplasty: The Use of Ophthalmic Viscoelastic Devices in Hypotonic Eyes That Had Undergone Glaucoma Filtering Surgeries.

PURPOSE: Descemet's stripping automated endothelial keratoplasty (DSAEK) is more difficult in hypotonic eyes with filtering bleb, due to the difficulties in elevating the intraocular pressure (IOP). We report a new method that uses ophthalmic viscoelastic devices (OVDs) to achieve good graft adhesion. CASE PRESENTATION: We performed modified DSAEK surgery on 2 eyes of 2 patients, who had previously undergone a trabeculectomy. Both eyes had functioning filtering blebs; the IOP was lower than 10 mmHg without medication. After the graft was inserted into the anterior chamber, the conjunctiva was penetrated, apart from the bleb, using a 30 G needle, and Healon V® was injected into the bleb until the encapsulated space was filled completely. Air was subsequently injected into the anterior chamber to promote the graft attachment to the back surface of the cornea. The IOP was elevated above 40 mmHg in both eyes 1 h after surgery and then decreased to less than 30 mmHg over the subsequent 3 h period. The implanted graft showed good adhesion and no dislocation. CONCLUSIONS: Our novel DSAEK procedure that adds one step of OVD injection into the filtering bleb may be useful for hypotonic eyes that had undergone filtering surgeries.

Use of Brilliant Blue G in Descemet's Membrane Endothelial Keratoplasty.

Vital staining of the endothelial graft is essential during Descemet's membrane endothelial keratoplasty (DMEK) to ensure surgical success. DMEK surgeons worldwide commonly use trypan blue (TB) to this end. However, TB may exert toxic effects on both the cornea and retina. Recently, Brilliant Blue G (BBG) has become recognized as an alternative stain for use during vitreoretinal surgery; BBG is associated with lower levels of toxicity. We retrospectively analyzed the utility of BBG staining during DMEK. We used 0.1% (w/v) BBG to stain the DMEK grafts of 12 patients. We evaluated the best spectacle-corrected visual acuity (BSCVA), central corneal thickness (CCT), and endothelial cell density (ECD) before and 3 and 6 months after surgery. BBG was effective in terms of graft visualization during DMEK. The BSCVA (log  MAR) improved from 0.99 ± 0.57 to 0.01 ± 0.07 (p < 0.05). The CCT decreased from 720.3 ± 58.1 µm preoperatively to 511.5 ± 50.6 µm at 6 months postoperatively (p = 0.0001). The ECD decreased from 2,754 ± 296 cells/mm2 to 1,708 ± 426 cells/mm2 at 6 months postoperatively (p < 0.001). The ECD loss was 37.9 ± 16.3%. The outcomes using BBG were comparable to those of earlier reports that employed TB; thus, BBG may be a viable alternative to TB.

Chandelier Illumination for Descemet Membrane Endothelial Keratoplasty.

PURPOSE: To describe a simple technique that uses posterior chandelier illumination during Descemet membrane endothelial keratoplasty in cases of severe bullous keratopathy (BK). METHODS: Five eyes of 4 patients with advanced BK undergoing Descemet membrane endothelial keratoplasty were retrospectively analyzed. The pupil of the host eye was not treated with mydriatic or miotic agents. The chandelier illuminator was inserted transconjunctivally into the vitreous cavity from the pars plana. RESULTS: In all eyes, BK was secondary to laser iridotomy, which was performed for prevention or treatment of angle closure glaucoma. The implanted graft was clearly confirmed in the anterior chamber using activated chandelier illumination. The graft was immediately attached to the host cornea, with eventual healing of BK in all eyes. No complication involving insertion or removal of the 25-gauge trocar and the chandelier illuminator was observed. No vision-threatening complication was observed in any of the 5 eyes. CONCLUSIONS: The chandelier illuminator provided good visibility of the anterior chamber and enhanced the safety of surgery by preventing formation of an inverted graft.

Use of four asymmetric marks to orient the donor graft during Descemet's membrane endothelial keratoplasty.

INTRODUCTION: Maintaining the correct orientation of the donor graft is important during Descemet's membrane endothelial keratoplasty (DMEK). We describe a new method of marking the donor graft prior to DMEK. METHODS: Twelve eyes of 10 patients with bullous keratopathy who underwent DMEK were retrospectively analysed. Donor discs were created by stripping the endothelium-Descemet's membrane layer from corneoscleral buttons. Four semicircular marks, two 1.0 mm and two 1.5 mm in diameter, were created at the edge of the donor disc. The small and large marks were paired. Each donor graft was inserted into the anterior chamber, unfolded and attached to the posterior corneal stroma with an air bubble. RESULTS: The inserted grafts were all appropriately orientated when attached to the back surfaces of the corneas. The two pairs of asymmetric marks afforded valuable guidance. Even when the graft was partially folded or decentred, and one pair of marks was obscured, the other pair was always visible to indicate graft orientation. Best spectacle-corrected visual acuity improved significantly in all patients (p<0.001). Compared with the preoperative endothelial cell density of the donor graft, that of the corneal endothelium had decreased 44.0%±10.0% by 6 months after surgery. CONCLUSIONS: Two pairs of asymmetrical semicircular marks placed on the edge of the donor graft allowed appropriate graft orientation during DMEK.

Techniques for Learning Descemet Membrane Endothelial Keratoplasty for Eyes of Asian Patients With Shallow Anterior Chamber.

PURPOSE: To describe several essential surgical techniques that overcome difficulties in performing Descemet membrane endothelial keratoplasty (DMEK) for inexperienced surgeons, especially those who perform DMEK on eyes of Asian patients. METHODS: Nine eyes of 9 Asian patients with bullous keratopathy who underwent DMEK were analyzed retrospectively. All patients were given a diuretic such as D-mannitol or acetazolamide shortly before surgery, with retrobulbar anesthesia and a Nadbath facial nerve block. Core vitrectomy before DMEK was performed in several cases in which a high vitreous pressure during surgery was predicted. The donor graft was stained with trypan blue, and a 25-G anterior chamber maintenance cannula was used to maintain the anterior chamber depth during graft insertion in all eyes. RESULTS: The cornea became clear in all eyes. The best spectacle-corrected visual acuity had improved significantly 6 months after the surgery compared with preoperative values (P = 0.026). The corneal endothelial cell density was 1371 cells per square millimeter at postoperative 6 months. CONCLUSIONS: Although DMEK is technically difficult, especially for inexperienced surgeons who operate on eyes of Asian patients, controlling anterior chamber pressure using various manipulations may help to prevent iatrogenic primary graft failure and lead to successful DMEK.