Preferred practice pattern for Descemet membrane endothelial keratoplasty surgeries: A survey of Indian corneal surgeons

Quick Response Code:Purpose: This study aims to assess the preferred surgical technique of Descemet membrane endothelial keratoplasty (DMEK) among corneal surgeons in India, and barriers in performing DMEK surgeries amongst the non-DMEK surgeons. Methods: An online, questionnaire-based, cross-sectional survey was conducted among members of the Cornea Society of India (CSI) (n = 500). Responses on their surgical experience, preferred technique, complications, and outcome of DMEK were collected and analyzed. Barriers in performing DMEK surgeries were assessed amongst the non-DMEK surgeons. Results: A total of 100 responses were obtained and response rate for the survey was 20%. DMEK was performed by 55% of the participants of whom only 40% had formal training in this technique. Surgical video-based learning was the most often used self-training method for others. Lack of training was the most common reason for not performing DMEK by the non-DMEK surgeons. Descemet stripping endothelial keratoplasty (DSEK) was the most common endothelial keratoplasty (EK) performed by both DMEK and non-DMEK surgeons. High volume (>50 cases) DMEK surgeries were reported by limited surgeons (n = 6). Nearly all the DMEK surgeons prepared the donor tissue by themselves on the day of the surgery, and majority felt that unrolling the graft in the anterior chamber was the most difficult surgical step. Nearly 80% of the DMEK surgeons were more comfortable with DSEK or Descemet stripping automated endothelial keratoplasty (DSAEK) when compared to DMEK. Conclusion: DMEK practice in India needs improvement with increased accessibility to DMEK training programs, wet lab facilities, and better support from eye banks.
Endothelial keratoplasty (EK) has seen a rapid evolution ever since its introduction in the mid-1950s by Charles Tillet. [bib_ref] Evolution of endothelial keratoplasty, Price [/bib_ref] [bib_ref] Endothelial Keratoplasty Update 2020, Price [/bib_ref] The technique of EK has advanced from posterior lamellar keratoplasty (PLK) to deep lamellar endothelial keratoplasty (DLEK), Descemet stripping endothelial keratoplasty (DSEK), Descemet stripping automated endothelial keratoplasty (DSAEK), Descemet membrane endothelial keratoplasty (DMEK), and pre-Descemet endothelial keratoplasty (PDEK). [bib_ref] Evolution of endothelial keratoplasty, Price [/bib_ref] [bib_ref] Endothelial Keratoplasty Update 2020, Price [/bib_ref] According to the various reports, DSEK/DSAEK and DMEK are the most commonly performed EKs.Reports from the Eye Bank Association of America and German keratoplasty registry report (2018) have revealed a constantly rising trend of DMEK surgeries [bib_ref] Trends in corneal transplantation from 2001 to 2016 in Germany: A report..., Flockerzi [/bib_ref] However, the world over, DSEK/DSAEK remains the most commonly performed EK. A steep learning curve, difficult surgical technique, a deficit of suitable donor tissue, and apprehension of postoperative complications are some of the reasons for the slow uptake of DMEK despite its described advantages over DSEK/DSAEK. [bib_ref] Perceived difficulties and barriers to uptake of Descemet's membrane endothelial keratoplasty among..., Zafar [/bib_ref] [bib_ref] Surgeon preference for endothelial keratoplasty techniques, Varadaraj [/bib_ref] [bib_ref] Learning descemet membrane endothelial keratoplasty: A survey of U.S. corneal surgeons, Koo [/bib_ref] [bib_ref] Descemet membrane endothelial keratoplasty (DMEK), Melles [/bib_ref] [bib_ref] DMEK versus DSAEK for Fuchs' endothelial dystrophy: A meta-analysis, Marques [/bib_ref] [bib_ref] Systematic review and meta-analysis of clinical outcomes of descemet membrane endothelial keratoplasty..., Singh [/bib_ref] Several steps of DMEK are considered technically challenging. These include preparation of DMEK roll, inserting graft in anterior chamber, unfolding the DMEK roll, and obtaining the correct orientation. [bib_ref] Perceived difficulties and barriers to uptake of Descemet's membrane endothelial keratoplasty among..., Zafar [/bib_ref] [bib_ref] Surgeon preference for endothelial keratoplasty techniques, Varadaraj [/bib_ref] [bib_ref] Learning descemet membrane endothelial keratoplasty: A survey of U.S. corneal surgeons, Koo [/bib_ref] With a limited number of fellowship programs for DMEK, the training of surgeons is often difficult. [bib_ref] Perceived difficulties and barriers to uptake of Descemet's membrane endothelial keratoplasty among..., Zafar [/bib_ref] [bib_ref] Surgeon preference for endothelial keratoplasty techniques, Varadaraj [/bib_ref] [bib_ref] Surgeon preferences for endothelial keratoplasty in Canada, Kisilevsky [/bib_ref] Learning through alternative methods like attending live surgery demonstrations, practicing in a wet lab facility, assisting a trained DMEK surgeon, or being assisted in the initial cases by a senior colleague, and surgical video-based learning have been described in the literature. [bib_ref] Perceived difficulties and barriers to uptake of Descemet's membrane endothelial keratoplasty among..., Zafar [/bib_ref] [bib_ref] Surgeon preference for endothelial keratoplasty techniques, Varadaraj [/bib_ref] [bib_ref] Learning descemet membrane endothelial keratoplasty: A survey of U.S. corneal surgeons, Koo [/bib_ref] [bib_ref] Learning DMEK from YouTube, Mckee [/bib_ref] [bib_ref] Artificial anterior chamber model using human donor corneas for DMEK surgical training, Fogla [/bib_ref] Koo et al. [bib_ref] Learning descemet membrane endothelial keratoplasty: A survey of U.S. corneal surgeons, Koo [/bib_ref] surveyed cornea surgeons based in the United States (US) who had started DMEK surgery within the last two years. The results highlighted the importance of mentorship and guidance of an experienced surgeon during the first few cases to reduce the rate of primary graft failure. Varadaraj et al. [bib_ref] Surgeon preference for endothelial keratoplasty techniques, Varadaraj [/bib_ref] conducted a similar study and described the preferences for DMEK surgery among US surgeons.
Various corneal surgeons have independently described their surgical technique of DMEK and its long-term outcome; however, limited literature is available on the corneal surgeons' preferred surgical practice pattern for DMEK. [bib_ref] Descemet membrane endothelial keratoplasty (DMEK), Melles [/bib_ref] [bib_ref] Sinsky hook assisted roll preparation (SHARP): A modified technique for Descemet membrane..., Maharana [/bib_ref] [bib_ref] Standardized DMEK technique: Reducing complications using prestripped tissue, novel glass injector, and..., Terry [/bib_ref] Varadaraj and Koo et al. reported the experience of DMEK surgeons in the US, and results from elsewhere are limited. [bib_ref] Surgeon preference for endothelial keratoplasty techniques, Varadaraj [/bib_ref] [bib_ref] Learning descemet membrane endothelial keratoplasty: A survey of U.S. corneal surgeons, Koo [/bib_ref] In India, there are limited opportunities for formal training programs for DMEK, a deficit of good quality donor corneas, and a limited number of cases suitable for DMEK due to delays in presentation. Hence, it is expected that the learning experience of DMEK surgeons and their preferred surgical practice pattern may be different when compared to other developed countries. In the current study, a survey was conducted among members of the Cornea Society of India (CSI) to estimate the number of surgeons performing DMEK and gather information regarding their DMEK training, experience, preoperative case selection, surgical technique, and postoperative complications and its management. Questions were also directed to the non-DMEK surgeons to understand the barriers in performing DMEK and methods to facilitate the adoption of this technique.

# Methods
A questionnaire-based, cross-sectional study was conducted among members of the CSI after approval from the institutional review board. The study adhered to the tenets of the Declaration of Helsinki.
A 33-question survey was developed using the SurveyMonkey website (Supplementary Content 1) after validation by three experts in the field of keratoplasty. The questions pertained to the surgeon's experience in keratoplasty, method of DMEK training, the experience of DMEK surgeries, preoperative case selection, donor tissue selection, preferred surgical technique for DMEK, postoperative complications, and challenges with DMEK. Various questions were directed toward specific surgical steps of DMEK. The questionnaire was pilot tested on 20 participants who had proficiency in the English language. The questionnaire was revised based on the findings of the pilot study.
A link to the validated questionnaire was emailed to all the cor-net group members, which is the official interactive forum for members of the Cornea Society of India. The email requested that the survey participants should be corneal surgeons based in India (Supplementary Content 2). The unique response link allowed completing the survey only once. The responses were collected, and data were exported to an Excel sheet. Statistical analysis was performed using SPSS software.

# Results

## Participant characteristics
A total of 500 cornea specialists were contacted through email, of which 100 responded (response rate of 20%). The majority of the participating ophthalmologists worked in a hospital setup (61%) while 39% worked in a private setup. [ [fig_ref] Table 1: Characteristics of Participating Cornea Surgeons WA -Weighted average [/fig_ref] ] The area of practice for 98% of participant cornea specialists was urban-suburban and only 2% were working in rural areas. The reported experience of performing keratoplasties was variable. One-third had an experience of >10 years, 45% of 5-10 years, and 22% of <5 years. Penetrating keratoplasty had been the most commonly performed procedure by the participant cornea specialist (Weighted average (WA) = 2.93) followed by the DSEK/DSAEK, anterior lamellar keratoplasty, and DMEK. Of the 100 participating cornea specialists, 55% (n = 55) stated that they performed DMEK. On the Chi-squared test, greater duration of experience (>10 years) of performing keratoplasties did not have a significant association with the surgeon performing or not performing DMEK (P = 0.0998). On enquiring about the type of EK performed by the participants, DSEK (WA = 2.13) was the most common procedure followed by DSAEK (WA = 1.24) and DMEK (WA = 1.04). Of the 55 DMEK surgeons, only 7.6% and 4.4% stated that it comprised 25%-50% and >50% of all their cases undergoing EK, respectively.

## Dmek training
Only 40% of the surgeons who performed DMEK had received formal training or fellowship in DMEK surgery. The rest reported surgical video-based learning (54.6%) and wet lab training (18.2%) as important methods of self-training [ [fig_ref] Table 2: Surgical Experience in DMEK of Participating DMEK Surgeons [/fig_ref] ]. Overall, a lack of formal training was the most common cause described by surgeons for not performing DMEK (48.9%). However, interestingly, one-third (31.3%) of the participating surgeons who had received training in DMEK did not perform this surgery. They stated anxiety related to donor cornea insertion or achieving correct orientation (30%) and donor cornea preparation (20%) as the major concerns for this inhibition. The majority of surgeons who did not perform DMEK suggested that short-term surgical training under an experienced surgeon (68.9%) would help perform DMEK while others felt wet lab training (13.3%) and assistance from senior surgeon trained in DMEK (13.3%) would be helpful in initiating DMEK surgery in their practice.

## Dmek experience
Among the surgeons who performed DMEK (n = 55), 63.6% (n = 35/55) reported an experience of <2 years in performing this technique and only 12.7% (n = 7/55) had > 5 years of experience [ [fig_ref] Table 2: Surgical Experience in DMEK of Participating DMEK Surgeons [/fig_ref] ]. A total of 43.6% of surgeons who performed DMEK reported performing <10 DMEK surgeries in a year. A high volume of DMEK surgeries (>50 cases/year) were reported by only six surgeons in this survey while a high volume of DSEK/DSAEK/Ultra-thin (UT) DSAEK was reported by 12 surgeons. On enquiring about the total number of DMEK surgeries performed, 16.4% of the surgeons (n = 9/55) who performed DMEK reported an experience of >50 surgeries with only seven surgeons having an experience of >100 surgeries.

## Dmek donor tissue selection
A majority (40.7%) of DMEK surgeons felt that the lower limit of donor age in DMEK should be 50 years [ [fig_ref] Table 3: Preferred Criteria for Donor Tissue Selection in DMEK [/fig_ref] ]. On enquiring about the preferred upper limit for donor age, a majority (29.6%) reported 70 years. However, out of six experienced surgeons (>50 DMEK surgeries and >5 years of DMEK experience), three suggested 80 years as the upper limit while one suggested that age does not matter. Donor endothelial cell density (ECD) cutoff of 2500 cells/mm 2 was preferred by the majority (40%, n = 22/55) followed by 2200 cells/mm 2 [ [fig_ref] Table 3: Preferred Criteria for Donor Tissue Selection in DMEK [/fig_ref] ].

## Dmek case selection
When asked about the patient exclusion criteria for DMEK, a majority (69.1%) reported corneal decompensation with ACIOL/SFIOL/aphakia as an exclusion criterion [ [fig_ref] Table 4: Preferred Descemet Membrane Endothelial Keratoplasty Technique [/fig_ref] ]. For cases presenting with corneal decompensation and coexistent cataract, 74.6% of surgeons (n = 41/55) performing DMEK preferred combined procedure (DMEK Triple) while 16.4% (n = 9/55) preferred staged procedure.

## Dmek surgical technique
Donor tissue preparation A majority of DMEK surgeons (94.6%, n = 52/55) preferred to prepare their donor corneas in the operation theatre [ [fig_ref] Table 4: Preferred Descemet Membrane Endothelial Keratoplasty Technique [/fig_ref] ].
Nearly all surgeons who prepared the donor tissue themselves preferred to prepare the tissue on the day of the surgery (n = 54/55). Among these surgeons who prepared the tissue on the same day, two-thirds (n = 36/54) prepared the DMEK roll before the surgery while one-third (n = 18/54) prepared it during the surgery. On enquiring about the preferred time taken to stain the DMEK roll, 36.4% of DMEK surgeons (n = 20/55) reported one minute. This was followed by 2 minutes (29.1%, n = 16/55), 30 seconds (20%, n = 11/55) and >2 minutes (14.6%, n = 8/55). The majority of DMEK surgeons (69.1%, n = 38/55) preferred an 8-mm size for DMEK graft followed by 7.5 mm (25.5%, n = 14/55). Only three surgeons reported the use of 8.5-mm graft size in their surgeries. None of the surgeons used graft sizes of <7.5 mm or >8.5 mm.

## Host preparation
When enquired about the host Descemet membrane endothelium complex stripping, 56.4% of DMEK surgeons (n = 31/55) opined on performing this step under an ophthalmic viscoelastic device (OVD) while 43.6% (n = 24/55) opined on performing this step under air. The majority of DMEK surgeons reported performing descemetorrhexis with a size greater than that of the graft (70.9%, n = 39/55) while 23.4% of surgeons (n = 13/55) preferred the same size descemetorrhexis as that of the graft. On the contrary, three surgeons preferred descemetorrhexis size smaller than the graft. On enquiring, if peripheral iridotomy (PI) was performed in all cases of DMEK, 90.9% of DMEK surgeons (n = 50/55) reported in favor of PI. When asked about the method used for PI, 92.7% of the DMEK surgeons (n = 51/55) performed an intraoperative PI while 7.3% (n = 4/55) performed a preoperative laser PI. Vitrector (45.5%) and Vannas scissors (41.8%) was used for making an intraoperative surgical PI by a majority of the DMEK surgeons.

## Graft insertion and tamponade
Indigenous injectors (IOL cartridge attached to a syringe) were used for the DMEK roll insertion by approximately half of the DMEK surgeons (52.7%, n = 29/55). Others reported the use of Geuder Glass Injector (29.1%), Modified Jones Tube (10.9%), and glass pipette (7.3%). On enquiring about the agent for tamponade after graft insertion, the majority of DMEK surgeons reported the use of air (94.6%, n = 52/55). Only three surgeons reported that they used iso-expansile concentration of SF6 for tamponade after graft insertion.

## Postoperative complications
A graft detachment rate of <10% was stated by approximately two-third (65.5%) of the DMEK surgeons while 14.5% stated a graft detachment rate of >25%. Only three surgeons reported >50% graft detachment rate. On being asked about the management of cases that developed partial graft detachment following DMEK, the majority of DMEK surgeons informed re-bubbling with air (52.7%, n = 29/55) but nearly one-third of surgeons (34.5%, n = 19/55) preferred to observe. Iso-expansile gas for re-bubbling was used by only 12.7% of DMEK surgeons (20% SF6-3.6%; 14% C3F8-9.1%). On enquiring about the management of cases that developed postoperative total graft detachment, approximately two-third answered that they preferred to re-bubble the graft (65.5%, n = 36/55). However, nearly one-third of DMEK surgeons (34.5%) informed that they preferred to proceed directly for re-graft (immediate re-graft -23.6%; Re-graft after 3-4 weeks -10.9%).

## Challenges with dmek
The most challenging step of DMEK perceived by the surgeons was unrolling of the DMEK graft in the anterior chamber (58.2%, n = 32/55). This was followed by achieving correct orientation of the graft (23.6%, n = 13/55), DMEK roll preparation (12.7%, n = 7/55), and DMEK roll insertion in the anterior chamber (5.5%, n = 3/55). The perceived difficulties by DMEK surgeons in various steps of DMEK have been expressed in terms of difficulty severity scale in [fig_ref] Figure 1: Surgeons' perceived difficulty severity scale for various surgical steps of DMEK [/fig_ref] When asked about their comfort in performing DMEK compared to DSAEK, the majority of surgeons reported that they were more comfortable in performing DSAEK/DSEK, while 10.9% described equal comfort levels with both the procedures. Only five surgeons (9.1%) stated being more comfortable with DMEK when compared to DSEK/DSAEK.

# Discussion
DMEK as a technique for EK has gained immense popularity among cornea surgeons during the last decade. Comparative studies between DSAEK/UTDSAEK and DMEK have shown better results with DMEK. [bib_ref] Systematic review and meta-analysis of clinical outcomes of descemet membrane endothelial keratoplasty..., Singh [/bib_ref] However, various surgeons show hesitancy in shifting from DSAEK to DMEK. The lack of formal training programs, steep learning curve, risk of donor tissue damage, and postoperative complications in DMEK are some of the reasons for this hesitancy. [bib_ref] Surgeon preference for endothelial keratoplasty techniques, Varadaraj [/bib_ref] [bib_ref] Learning descemet membrane endothelial keratoplasty: A survey of U.S. corneal surgeons, Koo [/bib_ref] In addition, a lot of variabilities have been observed in the surgical technique of DMEK from surgeon to surgeon. [bib_ref] Sinsky hook assisted roll preparation (SHARP): A modified technique for Descemet membrane..., Maharana [/bib_ref] [bib_ref] Standardized DMEK technique: Reducing complications using prestripped tissue, novel glass injector, and..., Terry [/bib_ref] [bib_ref] Microscope integrated intraoperative optical coherence tomography-guided DMEK in corneas with poor visualization, Sharma [/bib_ref] The current study aims to assess the barriers in performing DMEK, suggest methods to resolve and analyze the preferred techniques of DMEK amongst corneal surgeons in India.
In the current study, a total of 100 responses were obtained from the cornea specialists of India. Of the 100 participants, 55% performed DMEK. Another survey-based study conducted among cornea surgeons (n = 118) in the US reported that 59% of cornea specialists (n = 70) performed DMEK. [bib_ref] Surgeon preference for endothelial keratoplasty techniques, Varadaraj [/bib_ref] Hence, the proportion of cornea specialists performing DMEK appears to be similar in India when compared to the US. However, a similar study from Canada suggested that 78% of their cornea specialists performed DMEK. [bib_ref] Surgeon preferences for endothelial keratoplasty in Canada, Kisilevsky [/bib_ref] In our study, DSEK was the most performed EK by both non-DMEK as well as DMEK performing surgeons. Only 12% of the cornea surgeons who performed DMEK reported that DMEK constituted >25% of their total EKs. It is important to note that even though the majority of participating surgeons (83.6%; n = 46) had keratoplasty experience of >5 years, only a small subset of DMEK surgeons reported an experience in DMEK of >5 years duration (12.7%; n = 7) or performing >50 cases of DMEK (16.3%; n = 9). Hence, although many surgeons in India perform DMEK, DSEK is still the most performed type of EK and the list of experienced DMEK surgeons is limited.
In contrast, over one-third of the DMEK surgeons in the US have >10 years of experience in DMEK, suggesting that the uptake of this technique in the US was relatively early. [bib_ref] Surgeon preference for endothelial keratoplasty techniques, Varadaraj [/bib_ref] This is also attributed to the fact that in our country, the indications for keratoplasty are different, and the cases who require full thickness graft far outnumber the cases which require EK.
In the current study, lack of formal training was the most common reported cause by cornea surgeons for not performing DMEK, and a short-term surgical training under an experienced surgeon would be most helpful in performing DMEK. Surgical video-based learning was the most common alternative method of learning. Limited options for formal training in DMEK have led surgeons to resort to various methods of self-training. [bib_ref] Learning DMEK from YouTube, Mckee [/bib_ref] [bib_ref] Artificial anterior chamber model using human donor corneas for DMEK surgical training, Fogla [/bib_ref] [bib_ref] Partitioning an artificial anterior chamber with a latex diaphragm to simulate anterior..., Sales [/bib_ref] Watching surgical videos on YouTube, wet lab-based training, and watching live surgeries in conferences can be useful and have been reported in literature for self-training. [bib_ref] Learning DMEK from YouTube, Mckee [/bib_ref] [bib_ref] Artificial anterior chamber model using human donor corneas for DMEK surgical training, Fogla [/bib_ref] [bib_ref] Partitioning an artificial anterior chamber with a latex diaphragm to simulate anterior..., Sales [/bib_ref] Donor age cutoff for DMEK is still debatable. [bib_ref] Donor tissue characteristics in preparation of DMEK grafts, Gorovoy [/bib_ref] [bib_ref] Influence of donor characteristics on descemet membrane endothelial keratoplasty, Heinzelmann [/bib_ref] [bib_ref] Outcomes of descemet membrane endothelial keratoplasty using cornea from elderly donors aged..., Basak [/bib_ref] The majority of studies suggest that young donor tissues result in tight DMEK rolls which increases the chance of intraoperative manipulation and hence should be avoided. However, a few recent studies have shown comparable results between young and old donor tissues in DMEK. [bib_ref] Impact of donor age on descemet membrane endothelial keratoplasty outcome: Evaluation of..., Schaub [/bib_ref] [bib_ref] Younger donor tissue in descemet membrane endothelial keratoplasty surgery: Clinical outcomes, Hill [/bib_ref] Hill et al., [bib_ref] Younger donor tissue in descemet membrane endothelial keratoplasty surgery: Clinical outcomes, Hill [/bib_ref] reported that younger donors (<50 years) exhibit similar un-scrolling time, re-bubble rate, and endothelial cell loss when compared with older donors (>70 years). In the current study, the preferred lower age limit for donor tissue was 50 years, the upper age limit was 70 years, and ECD was 2500 cells/mm 2 . Using these cut-offs often limits the availability of donor tissue; hence there is a need to promote the use of younger and older donor tissues, especially among experienced surgeons.
DMEK donor tissue preparation requires surgical expertise. It is often a cause of apprehension, especially for novice surgeons, due to the risk of inadvertent tissue damage. Availability of pre-stripped, pre-marked, and pre-loaded donor tissue may be helpful for beginners as it reduces the apprehension involved with donor tissue preparation. Varadaraj et al. [bib_ref] Surgeon preference for endothelial keratoplasty techniques, Varadaraj [/bib_ref] suggested that nearly all of the surgeons (97.1%; n = 68/70) in their study used pre-stripped/pre-punched/pre-loaded donor tissue. On the contrary, in the present study, a majority of the surgeons (94.6%, n = 52/55) in India prepare their DMEK roll in the operating room themselves. Such a difference in practice may be due to the variation in eye bank facilities available across countries. Recent studies have suggested comparable clinical outcomes with the use of pre-loaded DMEK grafts when compared with a surgeon-prepared donor graft. [bib_ref] The last 200 surgeon-loaded descemet membrane endothelial keratoplasty tissue versus the first..., Potts [/bib_ref] [bib_ref] One-year clinical outcomes of preloaded descemet membrane endothelial keratoplasty versus non-preloaded descemet..., Bohm [/bib_ref] Hence, improving the eye bank standards and making pre-stripped/ pre-loaded donor tissue available to surgeons may decrease the stress of graft preparation and facilitate the surgery by shortening the operating time.
In the current study, the majority of surgeons described unrolling the DMEK graft and achieving correct orientation in the anterior chamber as the most difficult step. Training in a wet lab facility using simulator models and an artificial anterior chamber with latex diaphragm has been described in the literature for practicing various techniques to complete this step successfully. [bib_ref] Artificial anterior chamber model using human donor corneas for DMEK surgical training, Fogla [/bib_ref] [bib_ref] Partitioning an artificial anterior chamber with a latex diaphragm to simulate anterior..., Sales [/bib_ref] [bib_ref] Human ex vivo artificial anterior chamber model for practice DMEK surgery, Vasquez Perez [/bib_ref] Also, the majority of DMEK Sahay, et al.: Preferred Practice Pattern for DMEK surgeons (80%) were more comfortable with DSEK/DSAEK when compared to DMEK. In contrast, a study by Koo et al. [bib_ref] Learning descemet membrane endothelial keratoplasty: A survey of U.S. corneal surgeons, Koo [/bib_ref] reported that nearly 51% of DMEK surgeons were equally comfortable with DMEK when compared to DSEK/DSAEK. The stark difference suggests a need for improvement in the DMEK training and practice in India
The major limitations of the study include recall bias and self-selection bias, as seen in any other questionnaire-based survey. Also, the study had a low response rate and lack of information about the non-respondents. Hence, the results may not be generalized to all the cornea surgeons in India. However, the major advantage is that responses were obtained from a large section of DMEK surgeons with variable practice unlike previous studies which described the outcome from dedicated DMEK surgeons. Hence, considering the substantial number of responses received and lack of pre-existing data from this part of the world, the results of this study cannot be completely refuted.

# Conclusion
To conclude, the preferred technique of DMEK surgical steps discussed in the study can help surgeons in beginning DMEK surgery. In addition, formal training programs in DMEK, provision of a wet lab training facility, and support from eye banks with pre-loaded tissues can help novice surgeons to easily transition from DSEK/DSAEK to DMEK.

## Financial support and sponsorship
Nil.

## Conflicts of interest
There are no conflicts of interest.
[fig] Figure 1: Surgeons' perceived difficulty severity scale for various surgical steps of DMEK [/fig]
[table] Table 1: Characteristics of Participating Cornea Surgeons WA -Weighted average; PKP -Penetrating keratoplasty; ALK -Anterior lamellar keratoplasty; DALK -Deep anterior lamellar keratoplasty; DSEK -Descemet stripping endothelial keratoplasty; DSAEK -Descemet stripping automated endothelial keratoplasty; UTDSAEK; DMEK-Descemet membrane endothelial keratoplasty; PDEK -Pre-Descemet endothelial keratoplasty; KPro -Keratoprosthesis. * Chi-squared test [/table]
[table] Table 2: Surgical Experience in DMEK of Participating DMEK Surgeons [/table]
[table] Table 4: Preferred Descemet Membrane Endothelial Keratoplasty Technique [/table]
[table] Table 3: Preferred Criteria for Donor Tissue Selection in DMEK [/table]