Changes in endothelial cell density following penetrating keratoplasty and deep anterior lamellar keratoplasty

AIM: To compare the corneal endothelial cell density (ECD) of clear grafts after penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK). METHODS: The study included 44 and 54 patients treated with PK and DALK, respectively, between March 2006 and April 2010. Corneal ECD was examined using specular microscopy at postoperative 1, 3, 6, 12, and 18 months, and the values were compared. RESULTS: Corneal ECD reduction in the PK group was 7.4%, 15.2%, 23.5%, and 28.9% at 3, 6, 12 and 18 months respectively after surgery, compared with 4.2 % in the first month (P<0.01). These figures were 3.0%, 6.7%, 7.2%, and 7.7% at 3, 6, 12 and 18 months respectively, compared with 2.2 % in the first month in the DALK group (P>0.05). CONCLUSION: Compared with DALK,PK significantly reduced ECD of the clear grafts. These results suggest that survival of endothelial cells in grafts is better after DALK than after PK.     

穿透性角膜移植术后角膜植片内皮慢性失功的临床分析

目的探讨圆锥角膜行穿透性角膜移植（PK）术后角膜植片内皮慢性失功的临床特点。设计回顾性病例系列。研究对象圆锥角膜患者PK术后角膜植片内皮慢性失功148例（163眼）。方法所有患者实施PK术,采用非接触式角膜内皮显微镜、A型超声测厚仪和眼前节OCT扫描系统对角膜植片进行评价。主要指标中央角膜内皮细胞密度（ECD）、六边形细胞百分率、内皮细胞丢失率、内皮细胞形态、中央角膜厚度（CCT）及最佳矫正视力。结果PK术后3年内患者植片ECD呈下降趋势,内皮细胞年丢失率为14．2％±10．9％。术后1．5年较术后1年的ECD有明显下降（舟O．002）。术后不同时间点的植片内皮六边形细胞百分率均在50％以上,CCT在500μm以上,各组间比较无统计学差异（辟10．869）。PK术后5年以上复查,患者角膜植片ECD仍呈下降趋势,但个体差异性较大,多数患者的六边形细胞百分率仍在50％以上,内皮细胞面积增大是局部性的,CCT保持在500μm以上。150例未发生排斥的角膜植片除2例发生植片混浊外,其余均保持透明,患者术后最佳矫正视力提高。结论ECD的超生理下降和局部内皮细胞面积增大是PK术后角膜植片内皮慢性失功的主要临床表现。内皮慢性失功的发展存在个体差异性,且在同一个体不同时期发展程度亦有不同。     

Femtosecond laser-assisted deep anterior lamellar keratoplasty for keratoconus and keratectasia

AIM: To describe the initial outcomes and safety of femtosecond laser-assisted deep anterior lamellar keratoplasty (DALK) for keratoconus and post-LASIKkeratectasia.METHODS:In this non-comparative case series, 10 eyes of 9 patients underwent DALK procedures with a femtosecond laser (Carl Zeiss Meditec AG, Jena, Germany). Of the 9 patients, 7 had keratoconus and 2 had post-LASIK keratectasia. A 500 kHz VisuMax femtosecond laser was used to perform corneal cuts on both donor and recipient corneas.The outcome measures were the uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), corneal thickness, astigmatism, endothelial density count (EDC), and corneal power.RESULTS: All eyes were successfully treated. Early postoperative evaluation showed a clear graft in all cases. Intraoperative complications included one case of a small Descemet’s membrane perforation. Postoperatively, there was one case of stromal rejection, one of loosened sutures, and one of wound dehiscence. A normal corneal pattern topography and transparency were restored, UCVA and BCVA improved significantly, and astigmatism improved slightly. There was no statistically significant decrease in EDC.CONCLUSION: Our early results indicate that femtosecond laser-assisted deep anterior lamellar keratoplasty could improve UCVA and BCVA in patients with anterior corneal pathology. This approach shows promise as a safe and effective surgical choice in the treatment of keratoconus and post-LASIK keratectasia.     

Changing trends in corneal graft surgery: a ten-year review

AIM: To review indications and corneal tissue use for penetrating and lamellar surgery between 2002 and 2011. METHODS: The surgical reports of corneal grafts performed during 2002-2011, using tissues supplied by the Eye Bank of Piedmont (Italy), were reviewed retrospectively. Patient demographic data, date of intervention, indication for surgery, and surgical technique used were recorded. Surgical techniques included penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK) and endothelial keratoplasty (EK). The χ2 test was used to compare the distribution of indications and types of surgical technique used, for corneal grafts done during 2002-2006 versus those done during 2007-2011. RESULTS: The number of corneal grafts increased by 30.7% from 2002-2006 to 2007-2011 (from 1567 to 2048). Comparing the two periods, both main indications and surgical techniques changed significantly. In 2007-2011, the proportion of interventions for aphakic/pseudophakic bullous keratopathy (from 16.8% to 21.3%), graft failure (from 16.4% to 19.1%) and Fuchs endothelial dystrophy (from 12.8% to 16.7%) all increased significantly (P<0.05), while those for keratoconus decreased significantly (from 35.6% to 27.3%; P<0.001). In 2007-2011, the proportion of PK decreased significantly (from 92.4% to 57.2%; P<0.001) while that of EK and DALK went from 0.4% to 30.2% (P<0.001) and from 7.2% to 12.6% (P<0.001) respectively. CONCLUSION: During 2002-2011 the number of interventions increased significantly for corneal endothelial diseases and graft failure. The growing demand for interventions for these diseases corresponded to the widespread adoption of EK techniques. The use of DALK also increased, but more moderately than EK procedures.     

Deep anterior lamellar keratoplasty in the management of keratoconus

Advanced cases of keratoconus often require surgical intervention to restore corneal anatomy and improve eyesight. Penetrating keratoplasty (PK) although commonly performed has potential risk of immunological rejection and is now no longer automatically the first choice of surgery. DALK procedures have evolved, which allows surgical replacement of recipient''s corneal stroma, leaving behind healthy descemet membrane (DM) and endothelium. This reduces the risk of allograft endothelial rejection and late graft failure. In recent times, DALK techniques have led to significant improvements in visual outcome and current results are comparable to PK. Big bubble technique of DALK has become the most popular among the various surgical techniques described. Manual near DM DALK also gives good outcome although the visual recovery is often delayed. Future integration of femtosecond laser technology along with diagnostic imaging technology is likely to further improve outcomes of DALK in keratoconus.     

Comparison of Clinical Outcomes of Same-size Grafting between Deep Anterior Lamellar Keratoplasty and Penetrating Keratoplasty for Keratoconus

Purpose

To compare the clinical outcomes between deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PKP) with same-size grafts in patients with keratoconus.

Methods

Medical records of 16 eyes from 15 patients treated from June 2005 through April 2011 were retrospectively reviewed. Patients with contact lens intolerance or who were poor candidates for contact lens fitting due to advanced cone underwent keratoplasty. The transplantations consisted of 11 DALK and 5 PKP with same-size grafting for keratoconus. Best-corrected visual acuity (BCVA), refractive error, corneal topographic profiling, and clinical course were compared between DALK and PKP groups.

Results

The follow-up period was 30 ± 17 months in the DALK group and 45 ± 20 months in the PKP group (p = 0.145). At final follow-up, the DALK and PKP groups achieved a BCVA (logarithm of the minimum angle of resolution) of 0.34 and 0.52, respectively (p = 0.980). Postoperative refractive error and mean simulated keratometric index showed myopic astigmatism in both groups without any statistical difference. Corneal irregularity index measured at 5 mm in the DALK group was less than that of the PKP group at 1-year follow-up (p = 0.021); however, at final follow-up, there was no longer a statistically significant difference. Endothelial cell counts were lower in the PKP group than in the DALK group at final follow-up (p = 0.021).

Conclusions

The optical outcomes of DALK with same-size grafts for keratoconus are comparable to those of PKP. Endothelial cell counts are more stable in DALK compared to PKP.     

Mushroom keratoplasty in pediatric patients

Objective

To report the outcome of mushroom keratoplasty for the treatment of full thickness corneal disease in pediatric patients with healthy endothelium.

Methods

A retrospective analysis of pediatric patients who underwent mushroom keratoplasty. The medical records of pediatric patients suffering from full thickness corneal stromal disease with normal endothelium who underwent mushroom keratoplasty at our Institution were included. A two-piece donor graft consisting of a large anterior stromal lamella (9.0 mm in diameter and ±250 μm in thickness) and a small posterior lamella (5–6.5 mm in diameter) including deep stroma and endothelium, prepared with the aid of a microkeratome had been transplanted in all cases. Ophthalmic examination including slit lamp examination, best corrected visual acuity, and corneal topography was performed preoperatively and at each postoperative visit on all patients. The endothelial cells were assessed by specular microscopy in these patients.

Results

Six eyes of six patients (five males and one female) were included. The mean age was 9.3 years (range 5–15 years). Average follow-up was 17.8 months (range 9–48 months).There were no early or late complications recorded. All corneas were clear at the last follow up visit.Preoperative best corrected visual acuity (BCVA) was worse than 20/70 in all six eyes. Postoperatively, four eyes achieved BCVA of 20/40 or better.Endothelial cell loss (n eyes = 3 averaged 24% (range 19–31%). The mean endothelial cell loss was 24% (range 19–31%) among these patients.

Conclusions

Microkeratome assisted mushroom keratoplasty is a viable surgical option for pediatric eyes with full thickness corneal stromal disease and healthy endothelium. Mushroom keratoplasty combines the refractive advantage of a large penetrating keratoplasty with the survival advantage of a small penetrating keratoplasty. Furthermore, mushroom keratoplasty exhibits the mechanical advantage of a shaped keratoplasty.     

Modified deep anterior lamellar keratoplasty for the treatment of advanced keratoconus with steep corneal curvature to help in eliminating the wrinkles in the Descemet's membrane

Aims:

To determine the clinical efficacy of modified deep anterior lamellar keratoplasty (DALK) for the treatment of advanced-stage keratoconus with steep curvature.

Materials and Methods:

In this interventional, non-comparative case series, 30 patients with advanced stages of keratoconus and curvature of more than 60 D underwent a modified DALK procedure. In this technique, after big-bubble formation, posterior stromal lamella was cut and removed 5 mm centrally (baring Descemet''s membrane completely) with posterior stromal layer remaining peripherally.

Results:

The study included 30 eyes (30 patients with a mean ± SD age of 25 ± 5.4 years). The follow-up examination was performed for all participants up to 12 months after the surgery. The mean uncorrected visual acuity (UCVA) increased from 20/800 before the surgery to a subsequent 3/10 (P =0.12). Likewise, best spectacle corrected visual acuity (BSCVA) improved, reaching 6/10 postoperatively (former quantity 20/200) (P =0.18). In addition, mean keratometry and keratometric astigmatism managed to achieve considerable improvement, from 58.8 ± 5.4 D to 46.5 ± 2.1 D and 7.8 ± 2.1 to 4.54 ± 1.54 D, respectively (P =0.52). Descemet''s membrane wrinkling was not seen in any patient postoperatively.

Conclusions:

This technique is effective in restoring acceptable vision and corneal regularity in advanced cases of keratoconus with a curvature more than 60 D who are also at risk of Descemet''s membrane wrinkling after DALK. Therefore, this procedure could prevent from Descemet membrane wrinkling in such cases.     

Five-year endothelial cell count post penetrating keratoplasty using internationally-transported corneal donor tissue

Aim

To study the five-year endothelial cell loss in patients having undergone penetrating keratoplasty (PKP) and who received corneal donor tissue from international eye banks.

Deep Anterior Lamellar Keratoplasty Using Irradiated Acellular Cornea with Amniotic Membrane Transplantation for Intractable Ocular Surface Diseases

Purpose

To report the clinical outcomes of deep anterior lamellar keratoplasty (DALK) when sterile gamma-irradiated acellular corneal tissues (VisionGraft) are used in combination with amniotic membrane transplantation (AMT) for intractable ocular surface diseases.

Methods

The medical records of fifteen patients who had DALK with AMT were retrospectively reviewed. Indications for surgery included ocular burn, bacterial keratitis, herpes simplex virus keratitis, corneal opacity with Stevens-Johnson syndrome, Mooren''s ulcer, idiopathic myxoid degeneration of corneal stroma, and recurrent band keratopathy. DALK was performed using partial-thickness acellular corneal tissue and a temporary amniotic membrane patch was added at the end of the operation.

Results

All cases that underwent DALK with AMT became epithelialized within 2 postoperative weeks. Twelve patients showed favorable outcomes without graft rejection, corneal opacification, or neovascularization. The other three grafts developed corneal opacification and neovascularization, and required additional penetrating keratoplasty (PK). Unlike the results of previous PKs, there were no graft rejections and the graft clarity was well-maintained in these three cases for at least 8 months after PK.

Conclusions

DALK using sterile acellular corneal tissues in combination with AMT may be a good therapeutic strategy for treating intractable ocular surface diseases because of lowered immune rejection, fibroblast activation, and facilitation of epithelialization. Furthermore, DALK can help stabilize the ocular surface, prolong graft survival, and may allow better outcomes when combined with subsequent PK.     

Corneal biomechanical properties in eyes with no previous surgery, with previous penetrating keratoplasty and with deep anterior lamellar keratoplasty

Purpose

To compare the biomechanical properties of the cornea in eyes with no previous surgery, with keratoconus with previous penetrating keratoplasty (PK) and with keratoconus with previous deep anterior lamellar keratoplasty (DALK) using the Reichert Ocular Response Analyzer (ORA).

Methods

One hundred twenty eyes of 120 patients were included in this prospective comparative study. Forty eyes were with no previous ocular surgery (group 1), 40 eyes were with previous PK for keratoconus (group 2), and 40 eyes were with previous DALK for keratoconus (group 3). Corneal hysteresis (CH) and the corneal resistance factor (CRF) were measured with ORA.

Results

The CH and CRF values in group 2 were significantly lower than in group 1 and group 3 (p = 0.001). The CH and CRF values were similar in group 1 and group 3. There was no statistically significant difference between group 1 and 3.

Conclusion

Although the post-PK keratoconus cornea has weaker biomechanical properties, post-DALK keratoconus cornea is similar to normal cornea. A cornea weakened by keratoconus can be strengthened with lamellar keratoplasty.     

Comparison of deep anterior lamellar keratoplasty and penetrating keratoplasty with respect to postoperative corneal sensitivity and tear film function

Purpose

To investigate tear film function, central and peripheral corneal sensitivity and corneal subbasal nerve morphology in the cornea after deep anterior lamellar keratoplasty (DALK) compared with penetrating keratoplasty (PK).

Methods

This prospective study compared the changes in 16 eyes of 16 patients who underwent DALK (DALK group) with those in 28 eyes of 28 patients who underwent PK (PK group). Thirty healthy volunteers were also included as controls. Tear functions were evaluated using tear break-up time (TBUT), tear meniscus height (TMH) and corneal fluorescein staining. Corneal sensation was measured with a Cochet-Bonnet esthesiometer. Corneal subbasal nerve morphology was evaluated using in vivo confocal microscopy (IVCM). The patients were examined 1, 3, 6, 9 and 12 months after keratoplasty.

Results

Postoperatively, TMH recovered significantly faster in the DALK group than in the PK group (p?p?p?p?Conclusions Tear film function was restored more rapidly after DALK compared with PK, but there was no significant difference in corneal sensitivity between PK and DALK.     

Femtosecond laser enabled keratoplasty for advanced keratoconus

Purpose:

To assess the efficacy and advantages of femtosecond laser enabled keratoplasty (FLEK) over conventional penetrating keratoplasty (PKP) in advanced keratoconus.

Materials and Methods:

Detailed review of literature of published randomized controlled trials of operative techniques in PKP and FLEK.

Results:

Fifteen studies were identified, analyzed, and compared with our outcome. FLEK was found to have better outcome in view of better and earlier stabilization uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), and better refractive outcomes with low astigmatism as compared with conventional PKP. Wound healing also was noticed to be earlier, enabling early suture removal in FLEK.

Conclusions:

Studies relating to FLEK have shown better results than conventional PKP, however further studies are needed to assess the safety and intraoperative complications of the procedure.     

Outcomes of keratoplasty in a cohort of Indian patients with xeroderma pigmentosum

Purpose:To evaluate the outcomes of keratoplasty for xeroderma pigmentosum (XP) performed at a tertiary eye care center.Methods:A retrospective review of medical records of those patients who were clinically diagnosed to have XP (54 eyes of 36 patients) and underwent keratoplasty; either deep anterior lamellar keratoplasty (DALK, four eyes), endothelial keratoplasty (EK, eight eyes), or penetrating keratoplasty (PK, 42 eyes) from 1994 to 2018.Results:The median age at surgery was 20.6 years (interquartile range [IQR], 14.6–27.6 years) and 20 (55.6%) were males. Graft failure occurred in 15 eyes (35.7%) in the PK group and two eyes (50%) in the DALK group; none failed in the EK group. The probability of graft survival in the PK group was 97.2% ± 2.7% at 1 year, 74.0% ± 8.0% at 2 years, and 54.8% ± 11.7% at 5 years. In the PK group, 13 eyes needed antiglaucoma medications, 11 eyes developed graft infiltrate, and 13 eyes needed secondary interventions (cataract surgery, excision biopsy, and tarsorrhaphy). In the EK group, three eyes needed secondary interventions (excision biopsy). Median postoperative endothelial cell density at the last follow-up in the PK group was 1214 cells/mm² (IQR, 623–2277 cells/mm²).Conclusion:Despite the complexities of the ocular surface and adnexal issues in XP, keratoplasty had reasonably good outcomes. More than half of the PK grafts survived 5 years with no failures in the EK group. Regular follow-up and timely management of suture-related infections raised intraocular pressure, and suspicious ocular surface lesions, in addition to solar protection, are important for the success of keratoplasty in these eyes.     

甘油冷冻保存角膜深板层角膜移植术治疗圆锥角膜

目的分析甘油冷冻保存角膜深板层角膜移植术（DALK）治疗圆锥角膜术后角膜内皮细胞密度及屈光状态变化。方法回顾性病例研究。分析圆锥角膜患者用甘油冷冻保存的角膜材料行DALK治疗的44例（49眼）病例资料,其中17例（17眼）患者于术后1个月、1年、2年、3年、4年按期进行随访,且随访资料完整。分析术后角膜内皮细胞丢失率、视力以及屈光状态。结果患者平均随访时间为（39．0±12．6）个月,无一例发生植片免疫排斥。术前平均内皮细胞密度（ECD）为（2597±578）个／mmz．术后1个月、1年、2年、3年、4年时平均ECD为（1790±409）cells／mm2、（1703±443）cells／mm2,（1632±389）cells／mm2、（1638±357）cells／mm2、（1675±283）cells／mm2、（1611±421）cells／mm2。术后4年ECD较术前减少34．2％。术前平均裸眼视力（UCVA）为（1．40±0．60）logMAR,平均最佳矫正视力（BCVA）（0．98±0．54）logMAR,术后1个月、1年、2年、3年、4年平均BCVA分别为（0．44±0．12）logMAR、（0．36±0．20）logMAR、（0．32±0．23）logMAR、（0．29±0．20）logMAR、（0．27±0．16）logMAR。结论使用甘油冷冻保存的角膜材料的角膜移植术治疗圆锥角膜可获得较好的视力,角膜内皮细胞丢失率低．远期疗效较好。     

A simple surgical technique for splitting a single donor cornea for performing deep anterior lamellar keratoplasty and Descemet membrane endothelial keratoplasty without using a microkeratome

Purpose:To describe a simple manual surgical technique for splitting a single-donor eye for performing both deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK) without using a microkeratome.Methods:Twenty-three eyes with anterior stromal pathology and 23 eyes with irreversible endothelial dysfunction were evaluated for keratoplasty at a tertiary eye care referral center. Twenty-three healthy donor corneas were split into two parts. The Descemet’s membrane was stripped and used for DMEK. The stripped stroma was used for DALK. Best-corrected visual acuity (BCVA) of both DALK and DMEK, endothelial cell density, and endothelial cell loss in DMEK were noted at 1-year follow-up, along with any intraoperative or postoperative complications and failures.Results:In the DALK group, mean BCVA improved from 1.264 ± 0.25 log Mar preoperatively to 0.355 ± 0.27 log Mar at 12 months follow-up. There were no complications and failures. In the DMEK group, mean BCVA improved from 1.537 ± 0.61 log Mar preoperatively to 0.592 ± 0.67 log Mar and the mean donor ECD was 3071.66 (range, 2783–3487) cells/mm² preoperatively, which was reduced to 1989.33 (range, 1546–2543) cells/mm² at 12 months follow-up indicating a mean endothelial cell loss of 35%. The failure rate was 21.7%.Conclusion:This study demonstrates that with a single donor corneal tissue, both DALK and DMEK can be performed successfully without any complications. Our technique will help corneal surgeons in all developing countries to cost effectively perform more lamellar surgeries and help in reducing the magnitude of corneal blindness without the need for expensive microkeratomes.     

Evaluation of corneal biomechanical properties following penetrating keratoplasty using ocular response analyzer

Purpose:

To evaluate corneal biomechanical properties in eyes that has undergone penetrating keratoplasty (PK).

Materials and Methods:

Retrospective observational study in a tertiary care centre. Data recorded included ocular response analyzer (ORA) values of normal and post-keratoplasty eyes [corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and cornea-compensated intraocular pressure (IOPcc)], corneal topography, and central corneal thickness (CCT). Wilcoxon signed rank test was used to analyze the difference in ORA parameter between post-PK eyes and normal eyes. Correlation between parameters was evaluated with Spearman''s rho correlation.

Results:

The ORA study of 100 eyes of 50 normal subjects and 54 post-keratoplasty eyes of 51 patients showed CH of 8.340 ± 1.85 and 9.923 ± 1.558, CRF of 8.846 ± 2.39 and 9.577 ± 1.631 in post-PK eyes and normal eyes, respectively. CH and CRF did not correlate with post-keratoplasty astigmatism (P =0.311 and 0.276, respectively) while a significant correlation was observed with IOPg (P =0.004) and IOPcc (P < 0.001).

Conclusion:

Biomechanical profiles were significantly decreased in post-keratoplasty eyes with significant correlation with higher IOP as compared with that in normal eyes.     

Long-term outcomes of penetrating keratoplasty in keratoconus:analysis of the factors associated with final visual acuities

AIM: To investigate the long-term results of penetrating keratoplasty (PK) in patients with keratoconus (KC) and to evaluate factors that might influence the final visual outcome.METHODS:We retrospectively reviewed the data of all patients with clinical KC who had undergone PK by a single corneal surgeon in a single center from May 1980 to December 2005. The age of the patients, preoperative best-corrected visual acuity (BCVA), corneal thickness, death to preservation time, and preservation to transplantation time were recorded. Additionally, postoperative complications such as graft rejection, development of glaucoma and specular microscopy were checked during the follow-up.RESULTS:Sixty-nine eyes from 69 patients were finally included. The follow-up period was 8.64±6.13y. Graft rejection occurred in 4 eyes of 69 cases (5.8%), and the time to graft rejection was 2.1±1.3y. A Kaplan–Meier survival analysis showed that the estimated cumulative probability of graft rejection at 6, 13, and 17y after PK were 95.6%, 90.0%, and 78.8%, respectively. When we evaluated factors that might influence final BCVA in eyes, no disparity donor-host trephine size (same graft size) as well as higher spherical equivalent, and average K-value were associated with higher final BCVA. (P=0.006, 0.051, 0.092, and 0.021 in eyes with follow-up <8y; P=0.068, 0.065, and 0.030 in eyes with follow-up ≥8y, respectively).CONCLUSION: The long-term results of PK in patients with KC were favorable with a high percentage of good BCVA. Less myopic change and low average K-reading, as well as a surgical technique using the same size donor-recipient button may provide better visual outcomes particularly in patients with KC.     

Suture pull-through insertion of graft donor in Descemet stripping automated endothelial keratoplasty: Results of 4-year follow-up

Purpose:

To report our clinical experience and 4-year follow-up results of Descemet stripping automated endothelial keratoplasty (DSAEK) with the suture pull-through insertion technique.

Methods:

This is a retrospective study of 195 eyes in which a posterior lamellar keratoplasty was performed between 2007 and 2011. The insertion of a folded donor lenticule was performed with a double-armed 10-0 suture using a straight transchamber needle and half-circle needle. Endothelial cell density was measured annually up to 4 years after the surgery, and cell loss was calculated based on the median preoperative donor endothelial cell density. Postoperative complications, primary graft failure, pupillary block, and dislocation of the donor tissue were assessed.

Results:

All patients underwent uncomplicated DSAEK. Data were available for 195 eyes (100%) at 1 year, 186 eyes (95.3%) at 2 years, 176 eyes (90.2%) at 3 years, and 160 eyes (82%) at 4 years. Median preop-erative donor endothelial cell density was 2688 cells/mm² [interquartile range (IQR) 207.5 cells/mm²], which decreased by 27% at 1 year (1956 cells/mm², IQR 264.8 cells/mm²), 31% at 2 years (1855 cells/mm², IQR 320.5 cells/mm²), 35% at 3 years (1756.5 cells/mm², IQR 306.5 cells/mm²), and 36% at 4 years (1709.5 cells/mm², IQR 288,0 cells/mm²). Nine patients (4.6%) had a dislocation of donor tissue; all were successfully reattached with a second air injection. Only three eyes (1.5%) developed graft failure. Pupillary block was present in 15 eyes (7.7%).

Conclusion:

DSAEK with suture pull-through insertion of donor graft represents a simplified and safe technique that has endothelial cell loss comparable with other techniques and low rates of intraoperative and postoperative complications.     

Influence of different keratoplasty techniques on the biomechanical properties of the cornea

Purpose: To evaluate and compare corneal biomechanical changes after deep anterior lamellar keratoplasty (DALK) versus penetrating keratoplasty (PK) using the ocular response analyzer (ORA). Methods: This prospective comparative study included 65 eyes (65 patients). Patients were divided into three groups: DALK (20 eyes), PK (25 eyes) and control group of normal subjects (20 eyes). Ocular response analyzer was used to measure corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann‐correlated intraocular pressure and cornea‐compensated intraocular pressure at 6 and 12 months postoperatively. Central corneal thickness (CCT) was measured using ultrasonic pachymetry. Results: Both mean CH and mean CRF were significantly lower in PK group (sutures on; 10.1 ± 1.11 and 9.6 ± 1.08 mmHg) than in DALK (sutures out; 12.25 ± 1.13 and 12.09 ± 1.05 mmHg) and control groups (12.98 ± 1.19 and 12.59 ± 0.94 mmHg) at 6 months, respectively (p < 0.0001). After 1 year, there was no statistically significant difference in mean CH and CRF between DALK (12.68 ± 1.11 and 12.18 ± 1.11 mmHg) and PK groups (still sutures on; 12.36 ± 1.32 mmHg, p = 0.39 and 11.83 ± 1.26 mmHg, p = 0.33, respectively); however, the mean CRF was significantly lower in the PK than the control group (p = 0.03). No statistically significant difference in mean CH or mean CRF was found between DALK and control groups at any time‐point. Conclusions: Compared with PK, DALK provides rapid return of normal corneal biomechanics, perhaps because of the combined healing at both the deep interface and graft margin, shorter period of steroid treatment and the intactness of Descemet membrane in these eyes.