Aetiology-specific comparison of long-term outcome of deep anterior lamellar keratoplasty for corneal diseases

Incidence and Clinical Features of Immunologic Rejection After Deep Anterior Lamellar Keratoplasty

PURPOSE

The aim of this study was to investigate the incidence and clinical features of immunologic rejection after deep anterior lamellar keratoplasty (DALK).

METHODS

This study included 411 patients (464 eyes, median age [interquartile range; IQR] 55.8 years [36.1-69.5]) who underwent DALK at Tokyo Dental College between June 1997 and 2021. Of 411 patients, 24 (24 eyes [5.2%], 51.9 years [IQR 31.6-65.4]) developed immunologic rejection. We characterized the clinical features, risk factors associated with immunologic rejection, and prognosis.

RESULTS

The interval between DALK and immunologic rejection was 14.5 (range, 5-78) months. Immunologic rejection occurred after cessation/reduction of topical steroid in 9 (47.4%) and suture removal in 4 eyes (21.1%). The postoperative duration of topical steroid use in eyes with immunologic rejection was significantly shorter (10.0 months, [IQR 6.0-14.0]) than those without immunologic rejection (28.3 [IQR 15.8-42.7], P = 0.001). Immunologic rejection manifested as stromal edema in 19 (100.0%), ciliary hyperemia in 17 (89.5%), keratic precipitates in 13 (68.4%), epithelial edema in 13 (68.4%), infiltration in 9 (47.4%), corneal opacity in 4 (21.1%), and Descemet membrane detachment in 2 eyes (10.5%). After treatment, corneal clarity was restored in 17 eyes (89.5%); however, immunologic rejection led to corneal endothelial decompensation in 2 eyes (10.5%). Endothelial cell density decreased from 1795.7 ± 722.6 to 1651.6 ± 655.6 cells/mm 2 after immunologic rejection ( P = 0.074).

CONCLUSIONS

Post-DALK immunologic rejection was associated with specific clinical triggers such as reduction/cessation of topical steroids or suture removal.

Effect of Keratoconus Stage and Classification Parameters on Deep Anterior Lamellar Keratoplasty Outcomes

PURPOSE

The aim of this study was to investigate the effect of the keratoconus (KC) stage according to the Amsler-Krumeich classification system and the parameters used in this classification on deep anterior lamellar keratoplasty outcomes.

METHODS

The preoperative KC stage was determined, and the presence of corneal scarring was noted. The preoperative and postoperative best-corrected visual acuity (BCVA), refractive error, mean central keratometry (K mean ) readings, topographic astigmatism, and minimum corneal thickness (CT) values were recorded. Intraoperative and postoperative complications were also noted.

RESULTS

One hundred thirty-seven eyes (54 eyes in stage 3-83 eyes in stage 4) were included in the study. The mean follow-up period was 42.20 ± 24.36 months. There was no statistically significant difference between stage 3 and 4 KC groups for postoperative BCVA, K mean , CT, spherical equivalent, and topographic astigmatism values (each P value >0.05). The effect of preoperative BCVA, K mean , CT, and refractive error values on postoperative BCVA could not be demonstrated ( P = 0.264). In addition, no statistically significant correlation was found between postoperative and preoperative values (each P value > 0.05). Although intraoperative Descemet membrane perforation and postoperative early suture loosening were observed more frequently in stage 4 KC than in stage 3 KC, the 2 groups were statistically similar for these and other complications (each P value >0.05).

CONCLUSIONS

The preoperative KC stage and the parameters used in classification are not useful in predicting postoperative deep anterior lamellar keratoplasty outcomes. The timing of the surgery should be planned with the awareness that the progression of the disease will not have a negative effect on outcomes.

Etiology-Specific Comparison of the Long-Term Clinical Outcome of Repeat Deep Anterior Lamellar Keratoplasty for Optical Indications

PURPOSE

The aim of this study was to evaluate the etiology-specific clinical outcomes and complications of repeat deep anterior lamellar keratoplasty (DALK) after failed DALK.

METHODS

This retrospective case study included 32 eyes of 27 patients who underwent repeat DALK of 450 cases of DALK performed for optical indications between 1997 and 2013. The patients were divided into 4 etiology-specific subgroups (the corneal dystrophy, ocular surface disease, stromal scar, and others) or those with or without limbal stem cell deficiency (LSCD). The clinical outcomes evaluated were graft survival, best-corrected visual acuity, endothelial cell density, and complications.

RESULTS

The mean postoperative follow-up duration was 69.6 ± 54.8 months. The 1-, 3-, and 5-year overall graft survival rate were 76.7%, 57.5%, and 38.8% respectively. The graft survival rate was the highest in the corneal dystrophy group ( P = 0.0014) and was significantly ( P = 0.0010) higher in eyes without LSCD than in eyes with LSCD. There were no significant differences in the graft survival rates between the previous and current DALK groups. The postoperative best-corrected visual acuity of all subjects improved significantly. The postoperative endothelial cell density did not decrease after repeat DALK. There were no significant differences in the incidence of complications between patients with and without LSCD, except the incidence of persistent epithelial defects.

CONCLUSIONS

Repeat DALK had favorable outcomes in all etiology-specific groups, whereas eyes with LSCD required careful assessment of the ocular surface to avoid graft failure due to persistent epithelial defects.

Immunopathogenesis of corneal graft rejection

The most common cause of corneal graft failure is corneal graft rejection (CGR). Although cornea is one of the immune-privileged sites, it can still get a rejection episode due to a breach in its natural protective mechanism. Both anatomical and structural properties of cornea and anterior chamber contribute toward its immune tolerance. Clinically, every layer of the transplanted cornea can get a rejection episode. A proper understanding of immunopathogenesis will help in understanding the various mechanism of CGR and the development of newer strategies for the prevention and management of such cases.

Mesenchymal Stem Cell Exosomes as Immunomodulatory Therapy for Corneal Scarring

Corneal scarring is a leading cause of worldwide blindness. Human mesenchymal stem cells (MSC) have been reported to promote corneal wound healing through secreted exosomes. This study investigated the wound healing and immunomodulatory effects of MSC-derived exosomes (MSC-exo) in corneal injury through an established rat model of corneal scarring. After induction of corneal scarring by irregular phototherapeutic keratectomy (irrPTK), MSC exosome preparations (MSC-exo) or PBS vehicle as controls were applied to the injured rat corneas for five days. The animals were assessed for corneal clarity using a validated slit-lamp haze grading score. Stromal haze intensity was quantified using in-vivo confocal microscopy imaging. Corneal vascularization, fibrosis, variations in macrophage phenotypes, and inflammatory cytokines were evaluated using immunohistochemistry techniques and enzyme-linked immunosorbent assays (ELISA) of the excised corneas. Compared to the PBS control group, MSC-exo treatment group had faster epithelial wound closure (0.041), lower corneal haze score (p = 0.002), and reduced haze intensity (p = 0.004) throughout the follow-up period. Attenuation of corneal vascularisation based on CD31 and LYVE-1 staining and reduced fibrosis as measured by fibronectin and collagen 3A1 staining was also observed in the MSC-exo group. MSC-exo treated corneas also displayed a regenerative immune phenotype characterized by a higher infiltration of CD163+, CD206+ M2 macrophages over CD80+, CD86+ M1 macrophages (p = 0.023), reduced levels of pro-inflammatory IL-1β, IL-8, and TNF-α, and increased levels of anti-inflammatory IL-10. In conclusion, topical MSC-exo could alleviate corneal insults by promoting wound closure and reducing scar development, possibly through anti-angiogenesis and immunomodulation towards a regenerative and anti-inflammatory phenotype.

Deep Anterior Lamellar Keratoplasty: Can All Ruptures Be Fixed?

PURPOSE

The aim of this study was to report our experience in managing different types of Descemet membrane (DM) ruptures during deep anterior lamellar keratoplasty (DALK).

METHODS

This study was a retrospective, consecutive, interventional case series of 1573 DALK procedures conducted on 1244 patients, performed between 2002 and 2017. Inclusion criteria consisted of a minimum of 24-month follow-up. DM rupture incidence, location, and surgical approach for repair were recorded. Postoperative measures were investigated only in eyes that experienced DM ruptures and included best spectacle-corrected visual acuity, endothelial cell loss, double anterior chamber, pupillary block, need for rebubbling, graft clarity, and rejection episodes.

RESULTS

One thousand four hundred forty-three eyes met the inclusion criteria. DM ruptures occurred in 119 eyes (8.25%). Seventy-eight percent of DM ruptures were microruptures (≤2 mm), and they occurred more frequently during manual DALK cases. Macroruptures were less frequent (22%), and they occurred more frequently during subtotal and total anterior lamellar keratoplasty (STALK-TALK) cases. In general, DM ruptures mainly occurred in the peripheral cornea (95% of cases). One hundred (84%) of the 119 ruptures resolved by the first postoperative day. Nineteen cases (16%) developed double anterior chamber; all resolved by using different strategies. No intraoperative penetrating keratoplasty conversion was recorded. Pupillary block occurred in 7 cases (5.9%), but no Urrets-Zavalia syndrome was observed. The average postoperative endothelial cell loss was 410 ± 39 cells/mm 2 (19%) at 1-year follow-up, and there was no significant difference between cases requiring a rebubbling and cases that did not ( P = 0.896). All grafts but one were clear at the last follow-up. Graft failure from endothelial decompensation occurred in this lone case (0.8%).

CONCLUSIONS

It is worth trying to repair all DM ruptures in DALK, and immediate penetrating keratoplasty conversion should be avoided. Understanding the physiomechanical mechanisms in DALK allows to correctly choose a proper rescue strategy to successfully repair DM ruptures.

Refractive surgery after deep anterior lamellar keratoplasty: a review of the literature

PURPOSE

The main objective of this work is to present an updated review of the different surgical procedures for the correction of residual refractive errors following deep anterior lamellar keratoplasty (DALK) surgery.

METHODS

A review of the literature was conducted using PubMed, Web of Science, and Scopus databases. The search was conducted in January 2022 and was limited to articles published in peer-reviewed journals. The information extracted from each publication included sample size, mean follow-up time, pre- and post-operative uncorrected (UDVA) and corrected distance visual acuity (CDVA), pre- and post-operative refraction and spherical equivalent (SE), safety and efficacy indexes and complications.

RESULTS

Residual ametropias, mainly high astigmatism and myopia, and the resulting anisometropia are likely to occur following DALK. They become a limiting factor and may lead to unsatisfactory visual restoration, therefore affecting patients' quality of vision and life. Alternative surgical interventions may be required to treat this residual ametropia, such as corneal refractive surgery or intraocular lens implantation. A total of 47 relevant articles were studied in detail. Different refractive surgery techniques have been shown to be effective and safe for the correction of ametropia following the DALK procedure and to improve the patient's quality of vision, although more research is needed to confirm long-term results.

CONCLUSION

The final refractive technique will depend on different factors, such as the amount of ametropia, the condition of the cornea or the patient's individual needs, economics, and occupational demands.

Outcome of Lamellar Graft Patching for the Treatment of Noninfectious Corneal Perforations

PURPOSE

The aims of this study were to evaluate the clinical outcome of lamellar graft patching used for treating noninfectious corneal perforations and to determine the clinical factors affecting tectonic integrity.

METHODS

This retrospective study includes a total of 71 eyes of 67 patients who underwent lamellar graft patching for the treatment of corneal perforations due to persistent epithelial defects secondary to limbal stem cell deficiency (LSCD, 21 eyes; 29.6%), peripheral ulcerative keratitis (17 eyes; 23.9%), neurotrophic keratitis due to herpes simplex keratitis (HSK, 14 eyes; 19.7%), and other causes (19 eyes; 26.8%). We evaluated the tectonic integrity of the globe, visual outcomes, and postoperative complications.

RESULTS

Tectonic integrity was achieved in 53 eyes (74.6%). The survival proportions of eyes that achieved clear grafts were 77.8% and 65.2% at 12 and 24 months, respectively. Graft failure was observed in 19 eyes (26.8%). The survival rate of tectonic integrity and eyes that finally achieved a clear graft was significantly worse in eyes with LSCD compared with those without ( P < 0.001). The logarithm of minimal angle resolution improved significantly from 1.79 ± 0.98 to 1.22 ± 0.87 at 12 months and 1.08 ± 0.81 at 24 months. Postoperative complications included cataract formation (32 eyes, 45.1%), intraocular pressure rise (23 eyes, 32.4%), recurrent perforations (15 eyes, 21.1%), infectious keratitis (14 eyes, 19.7%), recurrence of herpes simplex keratitis (7 eyes, 9.9%), and traumatic graft dehiscence (1 eye, 1.4%).

CONCLUSIONS

Lamellar graft patching is an effective and safe surgical treatment for noninfectious corneal perforations; however, careful attention to severe complications is necessary, especially in eyes with LSCD.

Evidence in the prevention of the recurrence of herpes simplex and herpes zoster keratitis after eye surgery

OBJECTIVE

Herpetic keratitis, either due to herpes simplex keratitis (HSK) or herpes zoster ophthalmicus (HZO), can recur after eye surgery.º Prophylaxis is postulated as necessary to avoid it. The objective of this study was to review the scientific evidence on the preventive methods used in the perioperative period in patients previously affected by HSK/HZO.

METHODS

An exhaustive search was carried out in the PubMed and Web of Science databases to identify relevant articles on prophylaxis and risk of recurrence of HSK/HZO in patients undergoing eye surgery up to 31 December 2019.

RESULTS

There is strong evidence that oral prophylaxis should be recommended after penetrating keratoplasty in patients who have previously had HSK/HZO. For other types of surgery, the evidence is less compelling. However, a latent period of inactivity should be considered between disease and oral prophylaxis.

CONCLUSIONS

Penetrating and lamellar keratoplasty, corneal crosslinking, cataract surgery, and photorefractive and phototherapeutic surgery cause an alteration of the subbasal nerve plexus of the cornea. Due to surgical trauma, as well as the modulation of the ocular immune response caused by steroids applied in the postoperative period, it is possible to induce the reactivation of HSK/HZO, which is common in some cases. Within this article, we discuss the available evidence for HSK/HZO prophylaxis in eye surgery. Further studies are necessary to define the real risk of HSK/HZO recurrence after ocular surgeries, particularly in cataract surgery, and to confirm the efficacy of perioperative prophylaxis with anti-HSK/HZO antivirals.

Rescue Technique to Solve Postoperative Refractory Double Anterior Chamber in Deep Anterior Lamellar Keratoplasty

PURPOSE

The purpose of this study was to describe a simple rescue technique to solve postoperative double anterior chamber refractory to rebubbling in deep anterior lamellar keratoplasty (DALK).

METHODS

This study analyzed consecutive patients who underwent DALK between June 2014 and March 2018 and required a postoperative reattachment of Descemet membrane because of macroperforation-led persistent double chambers. The technique entails placing anchoring sutures to attach Descemet membrane to the donor's posterior stroma. Anchoring sutures were removed within 1 month of surgery. The postoperative best spectacle-corrected visual acuity (BSCVA) [converted to logarithm of the minimum angle of resolution (logMAR) units], endothelial cell density (cells/mm2), graft survival, postoperative complications, and corneal astigmatism (diopters) were evaluated.

RESULTS

Five eyes from 5 patients were included in this study [5 women, 63.6 ± 6.0 yrs (32-80 yrs); mean follow-up duration, 72.0 ± 23.3 mo (30-100 mo)] (mean ± SD). The grafts survived successfully in all patients without primary or secondary graft failure. The best spectacle-corrected visual acuity improved from 1.26 ± 0.66 logMAR preoperatively to 0.25 ± 0.15 logMAR postoperatively (n = 5, P = 0.042). The endothelial cell density was 1468 ± 810 cells/mm2 at the last visit.

CONCLUSIONS

Macroperforation of Descemet membrane during DALK with incomplete removal of the stroma can lead to persistent double anterior chamber. This complication could be solved by the technique devised by this study.

Elevated Cytokine Levels in Aqueous Humor Are Associated with Peripheral Anterior Synechiae after Penetrating Keratoplasty

Peripheral anterior synechiae (PAS) after corneal transplantation leads to refractory glaucoma and permanent loss of vision. However, the exact mechanism remains elusive. This study aimed to evaluate the association between cytokine levels in the aqueous humor (AqH) and the progression of PAS after penetrating keratoplasty (PKP). We measured 20 cytokine levels in AqH and assessed the correlation with PAS progression after PKP in 85 consecutive patients who underwent PKP. We also evaluated age-dependent alterations in PAS and cytokine levels in DBA2J mice. PAS developed in 38 (44.7%) of 85 eyes after PKP. The incidence of intraocular pressure increase after PKP was significantly greater in eyes with PAS (26.3%) than in those without PAS (2%, p = 0.0009). The PAS area at 12 months after PKP was significantly positively correlated with the preoperative levels of interleukin (IL)-6, interferon (IFN)-γ and monocyte chemotactic protein (MCP)-1 (p ≤ 0.049). In the DBA2J mice, an experimental glaucoma model that developed PAS at 50 weeks, the AqH levels of IL-2, IL-6, IL-10, IFN-γ, tumor necrosis factor-α, MCP-1 and granulocyte-macrophage colony-stimulating factor (GM-CSF) significantly increased at 50 weeks compared to 8 weeks (p ≤ 0.021). In conclusion, inflammatory alterations in the AqH microenvironment, such as high preoperative specific cytokine levels, can lead to PAS formation and glaucoma.

Aqueous Cytokine Levels Are Associated With Progression of Peripheral Anterior Synechiae After Descemet Stripping Automated Endothelial Keratoplasty

Purpose

To evaluate the association between total protein and cytokine levels in aqueous humor (AqH) and the progression of peripheral anterior synechiae (PAS) after Descemet stripping automated endothelial keratoplasty (DSAEK).

Methods

This prospective study included 146 consecutive patients who underwent DSAEK. Preoperative levels of total protein and 20 cytokines in AqH were measured. Using three-dimensional anterior segment optical coherence tomography, we assessed the iridotrabecular contact (ITC) area before and at 3, 6, and 12 months after DSAEK. Correlations between the total protein and cytokine levels in the AqH and ITC area were analyzed.

Results

ITC was observed in 47 eyes (32.2%) after DSAEK. The ITC area increased from 2.00 ± 4.42 mm² preoperatively to 3.00 ± 6.85 mm² at 12 months. The total protein level in AqH was significantly higher in eyes with ITC progression than in those without (1.45 ± 1.03 mg/mL vs. 1.00 ± 0.57; P = 0.04) and was significantly positively correlated with the progression of ITC area after DSAEK (at 6 months, r = 0.311 and P = 0.005; at 12 months, r = 0.342 and P = 0.0004). The ITC area at 12 months was significantly correlated with the preoperative AqH levels of interleukin-8 (r = 0.252; P = 0.021), interferon-γ (r = 0.318; P = 0.009), and soluble intercellular adhesion molecule-1 (r = 0.292; P = 0.004). Multivariate analyses showed that the total protein levels in AqH and the presence of preoperative ITC were significant risk factors for increased ITC area after DSAEK (β = 0.193–0.574; all P < 0.02).

Conclusions

Higher preoperative total protein and specific cytokine levels in AqH were associated with ITC formation after DSAEK.

Translational Relevance

Our findings indicate that chronic pathological changes in AqH can cause PAS progression and glaucoma after DSAEK.

Deep anterior lamellar keratoplasty for corneal penetrating wounds

PURPOSE

To report our surgical experience of deep anterior lamellar keratoplasty (DALK) performed in eyes with scarring resulting from a corneal penetrating wound without tissue loss.

METHODS

Case series of three eyes of three patients that underwent DALK for poor vision due to a scar resulting from a previous corneal penetrating wound. Surgery was performed at least 1 year after the initial injury. Manual dissection technique was used in all cases. Preoperative and postoperative best correct visual acuity (BCVA), postoperative residual bed thickness, and postoperative endothelial cell count (ECC) were evaluated.

RESULTS

Preoperative BCVA ranged from 1.3 to 1.0 LogMAR. Two eyes were pseudophakic and one eye had a traumatic cataract. Manual DALK was successfully accomplished in all three cases. The mean residual recipient bed thickness was 103 µm (range 68-130 µm). The mean endothelial cell loss at the 6th month of follow-up was 6% (range 3%-11%) with a further 1% decrease at 4 years. One of the patients underwent cataract surgery and limbal relaxing incisions 1 year after DALK having a total endothelial cell loss of 4.8% at 2 years of follow-up. BCVA at 2 years of follow-up was 0.1 LogMAR (range 0.22-0.0 LogMAR). No episode of rejection was recorded, and all grafts remained clear at last follow-up (5 years, range 4-6 years).

CONCLUSIONS

Manual DALK should be considered in cases of corneal scars in optical zone resulting from penetrating wound.

Ocular surgery after herpes simplex and herpes zoster keratitis

PURPOSE

The recurrence of herpetic stromal keratitis (HSK) and herpes zoster ophthalmicus (HZO) has been reported after a variety of ocular surgeries. The aim of this study was to review the evidence on the preventive methods employed in the perioperative period in patients having undergone HSK/HZO.

METHODS

The PubMed and Web of Science databases were the main resources used to conduct the medical literature search. An extensive search was performed to identify relevant articles concerning the prophylaxis against and risk of HSK/HZO recurrence in patients undergoing ocular surgery up to December 31, 2019.

RESULTS

The disturbance of the corneal nerve plexus occurs during several ocular surgeries including penetrating keratoplasty, lamellar keratoplasty, corneal cross-linking, cataract surgery, as well as photorefractive and phototherapeutic procedures. Such trauma, as well as modulation of the ocular immunological response caused by steroids applied postoperatively, might engender the HSK/HZO reactivation which is not uncommon. There is strong evidence that oral prophylaxis should be recommended just after surgery in patients undergoing penetrating keratoplasty and having suffered from HSK/HZO. For other types of surgeries, the evidence is less compelling; nevertheless, a period of disease quiescence and oral prophylaxis should still be considered.

CONCLUSIONS

Within the article, we discuss the available evidence for HSK/HZO prophylaxis in ocular surgery. Additional studies would be required to define the real risk of HSK/HZO recurrence following eye surgeries, and particularly cataract surgery, and to confirm the utility of perioperative HSK/HZO prophylaxis.

Immune privilege in corneal transplantation

Corneal transplantation is the most successful solid organ transplantation performed in humans. The extraordinary success of orthotopic corneal allografts, in both humans and experimental animals, is related to the phenomenon of "immune privilege". Inflammation is self-regulated to preserve ocular functions because the eye has immune privilege. At present, three major mechanisms are considered to provide immune privilege in corneal transplantation: 1) anatomical, cellular, and molecular barriers in the cornea; 2) tolerance related to anterior chamber-associated immune deviation and regulatory T cells; and 3) an immunosuppressive intraocular microenvironment. This review describes the mechanisms of immune privilege that have been elucidated from animal models of ocular inflammation, especially those involving corneal transplantation, and its relevance for the clinic. An update on molecular, cellular, and neural interactions in local and systemic immune regulation is provided. Therapeutic strategies for restoring immune privilege are also discussed.

Incidence and Outcomes of Intraoperative Descemet Membrane Perforations During Deep Anterior Lamellar Keratoplasty

PURPOSE

To report the incidence and outcomes of intraoperative Descemet membrane (DM) perforations during deep anterior lamellar keratoplasty (DALK).

DESIGN

Retrospective, consecutive, interventional case series.

METHODS

A retrospective audit of all DALK cases performed from 2004 to 2015 in a tertiary center, with and without intraoperative DM perforations. We excluded cases with preexisting corneal perforations before surgery.

RESULTS

There were a total of 540 eyes, of which 101 (18.7%) had intraoperative DM perforations. These included 79 eyes (78.2%) with microperforations and 15 eyes (14.9%) with macroperforation. The most common steps at which DM perforation occurred intraoperatively were during deep lamellar dissection (32 cases; 31.7%), air injection (27 cases; 26.7%), and suturing (21 cases; 20.8%). Management of the DM perforations included a combination of intracameral air tamponade (49 cases; 48.5%), stromal patching (10 cases; 9.9%), fibrin glue (8 cases; 7.9%), and suturing of the defect (1 case; 1.1%). There were 2 eyes (2/540; 0.37%) that were converted to penetrating keratoplasty (PK). There were no significant differences in the postoperative unaided or best-corrected visual acuity, or in the numbers of patients with postoperative graft failure, graft rejection, or subsequent surgery at postoperative years 1 and 3.

CONCLUSIONS

DALK cases with DM perforations intraoperatively are often able to be managed without conversion to PK. Cases with DM perforations intraoperatively have equivalent visual acuity outcomes compared to those without DM perforations, and did not have any increased risk of graft failure, rejection, or subsequent surgery at postoperative years 1 and 3.

Impact of Corneal Higher-Order Aberrations on Visual Acuity After Deep Anterior Lamellar Keratoplasty in Treating Keratoconus

PURPOSE

To evaluate the incidence of the Descemet membrane (DM) folds after deep anterior lamellar keratoplasty (DALK) in treating keratoconus. We also evaluated the influence of DM folds and corneal higher-order aberrations (HOAs) on visual acuity after DALK.

METHODS

This retrospective study included 89 consecutive eyes of 87 patients who underwent DALK for the treatment of keratoconus at Tokyo Dental College Ichikawa General Hospital from April 2002 to June 2017. The presence or absence of DM folds was determined by slitlamp microscopy. Visual acuity after DALK was compared between the eyes with and without DM folds. Corneal HOAs of the anterior and posterior surfaces and the total cornea were measured by anterior segment optical coherence tomography. Correlations among the presence of DM folds, corneal HOAs, and visual acuity were analyzed.

RESULTS

The Descemet membrane folds developed in 28.1% (25/89) eyes after DALK for the treatment of keratoconus. However, there were no significant differences in postoperative visual acuity between the eyes with and without DM folds at 1, 3, 6, and 12 months (P=0.739, P=0.106, P=0.223, and P=0.186, respectively). The visual acuity at 12 months was significantly correlated with corneal HOAs within a 4-mm diameter (anterior surface: R=0.546, P=0.003; total cornea: R=0.506, P=0.007).

CONCLUSIONS

Larger corneal HOAs, but not the presence of DM folds, were associated with poor visual acuity after DALK. In treating advanced keratoconus with DALK, it is important to minimize postoperative corneal HOAs, although DALK improves visual acuity by reducing HOAs due to keratoconus.

Deep anterior lamellar keratoplasty: A surgeon's guide

Purpose

To review and highlight important practical aspects of deep anterior lamellar keratoplasty (DALK) surgery and provide some useful tips for surgeons wishing to convert to this procedure from the conventional penetrating keratoplasty (PK) technique.

Methods

In this narrative review, the procedure of DALK is described in detail. Important pre, intra, and postoperative considerations are discussed with illustrative examples for better understanding. A comprehensive literature review was conducted in PubMed/Medline from January 1995 to July 2017 to identify original studies in English language regarding DALK. The primary endpoint of this review was the narrative description of surgical steps for DALK, its pitfalls, and management of common intraoperative complications.

Results

A standard DALK procedure can be successfully performed taking into consideration factors such as age, ophthalmic co-morbidities, status of the crystalline lens, retina, and intraocular pressure. Careful trephination and dissection of the host cornea employing appropriate technique (such as big bubble technique, manual dissection, visco-dissection, etc.) suitable for the specific case is important to achieve good postoperative outcomes. Prompt identification of intraoperative complications such as double bubble, micro and macroperforations, etc. are vital to change the management strategies.

Conclusion

Although there is a steep learning curve for DALK procedure, considering details and having insight into the management of intraoperative issues facilitates learning and reduces complication rates.

Corneal Higher-order Aberrations and Visual Improvement Following Corneal Transplantation in Treating Herpes Simplex Keratitis

PURPOSE

To examine corneal higher-order aberrations (HOAs) and visual improvement following corneal transplantation in treating corneal scar caused by herpes simplex keratitis (HSK).

DESIGN

Retrospective consecutive case series.

METHODS

This study included a total of 52 eyes: 18 eyes of normal subjects, and 34 eyes of consecutive patients with corneal scar owing to HSK who underwent penetrating keratoplasty (PKP, 17 eyes) or deep anterior lamellar keratoplasty (DALK, 17 eyes). HOAs of the anterior, posterior surfaces and the total cornea were analyzed by anterior segment optical coherence tomography. The correlations between corneal HOAs and visual improvement were also analyzed.

RESULTS

Mean logarithm of the minimal angle of resolution (logMAR) visual acuity significantly improved from 1.40 ± 0.70 to 0.46 ± 0.45 after corneal transplantation (P < .0001). Mean corneal HOAs of the anterior surface significantly decreased after corneal transplantation (PKP: from 1.16 ± 0.59 μm to 0.58 ± 0.35 μm, P = .035, DALK: from 0.94 ± 0.57 μm to 0.37 ± 0.18 μm, P = .004). Visual acuity following corneal transplantation was correlated with the corneal HOAs at 12 months (r = 0.53, P = .01). Visual improvement at 3, 6, and 12 months was positively correlated with preoperative HOAs of the total cornea and posterior surface (all P < .01).

CONCLUSIONS

Preoperative corneal HOAs were associated with the visual improvement in treating corneal scar caused by HSK. Thus, the preoperative assessment of corneal HOAs, especially of the posterior surface, is important in the decision to perform corneal transplantation in eyes with HSK.

Long-term clinical outcome of femtosecond laser-assisted lamellar keratectomy with phototherapeutic keratectomy in anterior corneal stromal dystrophy

Purpose

To evaluate long-term outcome of femtosecond laser-assisted lamellar keratectomy (FLK) with phototherapeutic keratectomy (PTK) in patients with anterior corneal stromal dystrophies.

Methods

A total of 10 eyes from seven patients who underwent FLK were included. The patients had suffered from recurrent corneal erosion or visual disturbance in anterior corneal dystrophies (five Avellino dystrophies and two lattice dystrophies). Planar-shaped lamellar keratectomy was performed using femtosecond laser. The amount of corneal excision was determined by the depth of corneal opacity. Additional PTK with mitomycin C application was performed for smoothening of corneal cut surface. The patients were evaluated with following parameters: uncorrected visual acuity, best-corrected visual acuity (BCVA), mean anterior keratometric value, corneal irregularity, corneal high-order aberrations (HOA) and the recurrence of corneal erosion.

Results

Mean duration of follow-up was 64 months (2.5–9.5 years). The BCVA improved more than two lines of Snellen chart at last visit. The changes of keratometric values were within ±1 D in eight out of 10 eyes. Corneal irregularities in central 5 mm cornea and the values of total corneal HOA in central 6 mm cornea decreased by 0.3–3.1 D and 0.01–2.2 µm, respectively. Corneal erosion did not recur in any of those patients during follow-up and corneal dystrophy did not recur in eight out of 10 eyes.

Conclusion

In anterior corneal stromal dystrophies, FLK with PTK can be an effective surgical option to improve VA through decreasing corneal irregularities and HOA, while minimising corneal curvature changes.