Late corneal ectasia after penetrating and deep anterior lamellar keratoplasty for keratoconus

AIM:To investigate tomographic features of late corneal ectasia after keratoplasty for keratoconus and compare penetrating keratoplasty(PK)and deep anterior lamellar keratoplasty(DALK)in terms of incidence,time of onset and risk factors of corneal ectasia.METHODS:Sixty eyes with PK and 30 eyes with DALK operated between 1999 and 2021 were analyzed.Final Pentacam scans were evaluated together with vision and previous topographies.Main outcome measures were vision,K values,apparent thinning on graft-host cornea and the difference between opposing quadrants in the thinnest point measurements.Anterior segment optic coherence tomography was performed for further evaluation.RESULTS:Mean follow-up was 127.2mo(24–282mo)in PK,and 64.3mo(24–144mo)in DALK.K max was higher in DALK(60.6 vs 56.7 D,P=0.012).Inferior recipient was thinner(595.9μm)in PK than DALK(662.2μm,P=0.021),due to longer follow-up.Overall corneal ectasia rate was 20.0% within 24y.Ectasia rate was the same(6.7%)in DALK 2/30 and in PK 4/60 in 10y and 13.3%in 12y(4/30 and 8/60,respectively).It increased to 23.3%(14/60)in PK over 24y.While ectasia was not seen before 7y in PK,it could be seen in DALK starting from the 5^(th) year.The intervals between keratoplasty and ectasia were 144.5mo in PK and 99mo in DALK.Inferior recipient was significantly thinner in 18 eyes with ectasia(502.7μm)compared to 76 non-ectasia(649.1μm,P=0.000).Inferior graft was thinner(561.0 vs 620.4μm,P=0.006),K max(63.3 vs 56.5 D,P=0.000),and anterior elevation was higher in ectasia(89.1 vs 48.6μm,P=0.002).Accelerated crosslinking was performed on 5 eyes.CONCLUSION:Inferior-superior recipient and inferior graft thinning on tomography,with high K max and anterior elevation emerge as the most reliable criteria for the diagnosis of late ectasia.The incidence of corneal ectasia increases with the time.

Comparison of visual and topographic outcomes of deep-anterior lamellar keratoplasty and penetrating keratoplasty in keratoconus

AIM：To compare visual,surgical and topographic outcomes of deep anterior lamellar keratoplasty（DALK）and penetrating keratoplasty（PK）for keratoconus（KC）.METHODS：In this multicenter,prospective,randomized clinical trial 76 eyes of 71 KC patients operated between January 2011 and July 2014 in 2 tertiary referral hospitals were included. Consecutive patients were alternately selected to receive one of the two surgical methods. Thirty eight eyes underwent DALK with the big-bubble technique and 38 eyes underwent PK.RESULTS：Mean best spectacle corrected visual acuity（BSCVA）at the first postoperative week（P=0.012）and the first postoperative month（P〈0.001）was statistically significantly higher in DALK group. The mean BSCVA at12 mo was not significantly different for DALK（0.30±1.99 log MAR）versus PK（0.40±0.33 log MAR）（P=0.104）. The76.3% of the eyes had a BSCVA over 0.5 in DALK and 47.4%in PK group（P=0.009）. The 7.9% of the eyes had a BSCVA of 1.0 in DALK and 5.3% in PK group（P=0.644）. Mean spherical equivalent was-2.94 D in DALK and-3.09 D in PK group.Mean topographic astigmatism was 4.62 D and 4.18 D respectively. Regular topographic patterns were observed in 31（81.6%）of DALK and 29（76.3%）of PK（P=0.574）. The most frequent topographic pattern was oblate asymmetric bow tie,seen in 39.5% in DALK and 23.7% in PK. CONCLUSION：Big bubble DALK provides an earlier visual improvement compare to PK. However,visual and topographic outcomes are similar to those in PK at 1y. Postoperative complications including rejection and intraocular pressure elevation are more frequent in PK. DALK is a safer alternative to PK for KC. However,intraoperativeperforation of the Descemet＇s membrane is a significant complication.

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-LASIK keratectasia.·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 2had 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.

Comparison of long-term results after manual and femtosecond assisted corneal trephination in deep anterior lamellar keratoplasty for keratoconus

AIM: To compare long-term postoperative outcomes of manual and femtosecond assisted corneal trephination in deep anterior lamellar keratoplasty(FS-DALK) for keratoconus.METHODS: In the retrospective study, 17 consecutive eyes that underwent vertical side cut incision FS-DALK and 22 eyes that underwent trephine incision DALK were collected over a 2-year period. Main measurements included postoperative uncorrected-visual acuity(UCVA), corrected distance visual acuity(CDVA), refractive sphere and cylinder, manifest refraction spherical equivalent(MRSE), flat and steep corneal keratometry(K1 and K2), endothelial cell density(ECD), and time of epithelium healing and suture removal.RESULTS: Groups were comparable for diagnosis and preoperative visual acuity. Follow-up averaged 23 mo(range, 12-36 mo). At 12 mo, the mean UCVA was better in the manual-DALK group(P=0.039), and the refractive sphere was lower in the FS-DALK group(P=0.040). MRSE between groups differed at 1, 6, and 12 mo postoperatively(P=0.047, 0.025, 0.042, respectively). Mean CDVA, cylinder, K1, K2,corneal astigmatism, ECD, and time of epithelium healing were similar between groups. Stability of MRSE, ECD, and K1 returned sooner after FS-DALK. Initial loosened suture removal time was earlier in the manual-DALK group(P=0.042) while complete suture removal time was similar(P=0.122).CONCLUSION: Manual and femtosecond assisted corneal trephination in DALK are options for advanced keratoconus. FS-DALK do not result in improved visual acuity but it is more stable during the follow-up period. FSDALK in the present form show limited benefit, so surgical design and parameters still need to be optimized and explored.

Femtosecond laser-assisted deep anterior lamellar keratoplasty in phototherapeutic keratectomy versus the big-bubble technique in keratoconus

AIM：To compare the functional and anatomic results of femtosecond laser（FSL）-assisted deep anterior lamellar keratoplasty（DALK） associated with phototherapeutic keratectomy（PTK） and FSL-assisted DALK performed using the big-bubble technique in keratoconus.METHODS：During the first phase of the study,an electron microscopy histopathology pilot study was conducted that included four unsuitable donor corneas divided into two groups：in FSL group,FSL lamellar cuts were performed on two corneas and in FSL＋PTK group,PTK was performed at the stromal beds of two corneas after FSL lamellar cuts were made.During the second phase of the study,a randomized clinical trial was conducted that included two treatment groups of patients with keratoconus：group 1（n=14 eyes） underwent FSL-assisted DALK associated with PTK and group 2（n=12 eyes） underwent FSL-assisted DALK associated with the bigbubble technique.The main outcome measures were the postoperative visual acuity（VA） and optical coherence tomography（OCT） measurements,confocal microscopic findings,and contrast sensitivity.RESULTS：In the pilot study,histopathology showed a more regular stromal bed in the FSL＋PTK group.In the clinical trial,group 1 had significantly worse best spectaclecorrected VA and contrast sensitivity（P〈0.05 for both comparisons）.The residual stromal bed measured by OCT was significantly（P〈0.05） thicker in group 1.Confocal microscopy detected opacities only at the donor-receptor interface in group 1.CONCLUSION：Patients with keratoconus treated with FSL-assisted DALK performed using the big-bubble technique fare better than treated with FSL-assisted DALK associated with PTK.

Recurrence of keratoconus after deep anterior lamellar keratoplasty following pregnancy

Keratoconus is a progressive, non-inflammatory disease of the cornea, which is characterized by marked cornealsteepening and thinningrll. It induces myopia and irregular astigmatism leading frequently to severe visual impairmentu. Although several aetiological factors have been implicated in its pathophysiology, the exact mechanisms underlying keratoconus are not fully elucidated yet. Corneal crosslinking is the treatment of choice in order to inhibit the progression of keratoconus, whereas advanced cases require penetrating or lamellar keratolalasty for visual restoration.

Comparison of clinical outcomes of deep anterior lamellar keratoplasty and excimer laser assisted anterior lamellar keratoplasty in keratoconus

AIM: To compare and evaluate the clinical outcomes of deep anterior lamellar keratoplasty(DALK) and excimer laser assisted anterior lamellar keratoplasty(ELLK) in eyes with keratoconus.METHODS: In this study, 57 eyes of 56 patients operated between 2013 to 2017 were included. Thirty-one eyes underwent big-bubble DALK and twenty-six eyes underwent ELLK. Preoperative and at control visits complete ophthalmic examination was performed. RESULTS: The mean patient age at the time of DALK surgery was 27 y and mean follow-up period was 21±5.4 mo. The mean patient age at the time of ELLK surgery was 27 y and mean follow-up period was 40±18 mo. Mean best spectacle corrected visual acuity(BSCVA) at postoperative period was significantly higher for DALK group(0.66±0.11) versus ELLK group(0.4±0.2)(P<0.05). Descemet's membrane microperforation was occurred in 7 patients in DALK group versus in 1 patient in ELLK group. In 4 eyes, interface irregularity was developed in ELLK group. None of the patients in follow-up had graft rejection in both groups.CONCLUSION: In ELLK group, complication rate is lower, the surgical technique is simpler, faster and safer and also ELLK requires less experience with respect to DALK. Further, DALK can be performed unless satisfactory visual acuity is achieved after ELLK.

Donor cornea quality used for penetrating keratoplasty vs deep anterior lamellar keratoplasty

Deep anterior lamellar keratoplasty(DALK) has recently been introduced as an alternative procedure to penetrating keratoplasty(PK) for corneal pathologies not affecting the corneal endothelium. DALK does not rely on donor endothelium and requires less rigid criteria for donor corneal tissue quality. Therefore, DALK makes it possible to use donor corneas deemed unsuitable for PK. Furthermore, lamellar keratoplasty allows acellular corneal tissue to be transplanted. As a result, long-term preservation techniques are being revisited to increase the availability of donor corneas and subsequently alleviate constraints of availability, cost, storage, and transportation in many countries. The recent alterations in corneal transplantation techniques and hence the type of donor cornea tissues used for each technique, may require corneal surgeons and eye banks to reevaluate their selection criteria. The purpose of this systematic review is to present an updated analysis on the type and quality of donor corneas used for PK and DALK, assess the influence of donor and eye bank factors on the quality of donor corneas, and determine whether any of these donor factors affect clinical outcomes, complications, and graft survivals.

Two-step strategy—conjunctival flap covering surgery combined with secondary deep anterior lamellar keratoplasty for the treatment of high-risk fungal keratitis

AIM:To investigate whether the two-step strategy[conjunctival flap covering surgery(CFCS)combined with secondary deep anterior lamellar keratoplasty(DALK)]is effective for patients with high-risk fungal keratitis(FK).METHODS:In this noncomparative,retrospective case series,10 subjects(6 males,4 females)with a mean age of 56.5±7.1(range 47-72)y with high-risk FK undergone the two-step strategy were included.Reported outcome measures were healing of the corneal ulcer,recurrence of FK,reject reaction,improvement in best corrected visual acuity(BCVA)and relevant complications.RESULTS:The average diameter of corneal infiltrates was 7.50±0.39 mm,ranging from 6.94 to 8.13 mm.The mean depth of corneal infiltrates was 422.4±77.1μm,ranging from 350 to 535μm.The mean corneal thickness was 597.4±117.3μm,ranging from 458 to 851μm.Hypopyon and endothelial plaques were presented in all patients.The period between the two steps was 3.65±0.9(ranging from 3 to 5)mo.The graft diameter was 7.75±0.39 mm.At the last follow-up(average 9.25±3.39,ranging from 5.5 to 17mo),no fungal recurrence or graft rejection appeared,and all patients showed improvement of BCVA.One patient suffered from liver function impairment due to oral voriconazole for 4wk and recovered spontaneously after 1wk of drug withdrawal.CONCLUSION:The two-step strategy is safe and effective in the treatment of high-risk FK by transforming intentional therapeutic penetrating keratoplasty during acute infection to later optical DALK.It is a practical strategy,especially in areas lacking fresh donor corneas and eye bank services.

Indications for penetrating keratoplasty and anterior lamellar keratoplasty during 2010-2017

AIM: To review the indications of penetrating keratoplasty(PK) and anterior lamellar keratoplasty(ALK) at Qingdao Eye Hospital, Shandong Eye Institute, Qingdao, China, from 2010 to 2017. METHODS: The data of all patients undergoing PK or ALK from January 2010 to December 2017 was retrospectively reviewed, with the indications during 2010-2013 and 2014-2017 compared. RESULTS: A total of 1869 eyes were included, among which 1405 eyes(75.2%) had PK and 464 eyes(24.8%) had ALK. The leading indications were suppurative keratitis(36.8%), keratoconus(15.5%), herpes keratitis(13.1%), and regraft(10.5%). In eyes undergoing PK, the top four indications were suppurative keratitis(38.7%), herpes keratitis(15.3%), keratoconus(12.6%), and regraft(12.5%) during 2014-2017, with the proportion of suppurative keratitis and herpes keratitis decreased while regraft and keratoconus increased compared with 2010-2013. In eyes with ALK, suppurative keratitis(30.8%), keratoconus(24.1%), corneal dystrophies and degenerations(10.6%), and corneal dermoid tumor(9.7%) were the top four indications, and there was no significant difference for the proportion of each indication between 2010-2013 and 2014-2017. CONCLUSION: Suppurative keratitis is the most common indication for PK and ALK at Qingdao Eye Hospital during 2010-2017, followed by keratoconus, herpes keratitis, and regraft. In eyes treated with PK, the proportion of suppurative keratitis and herpes keratitis decrease while regraft and keratoconus increase during 2014-2017 compared with 2010-2013.

Phacoemulsification in eyes with corneal opacities after deep anterior lamellar keratoplasty

To evaluate the maneuverability and efficacy of phacoemulsification and intraocular lens(IOL) implantation in eyes with corneal opacities after deep anterior lamellar keratoplasty(DALK), twelve eyes of 12 patients with mild to moderate corneal opacities after DALK and coexisting cataracts were analyzed retrospectively. Phacoemulsification and IOL implantation assisted with anterior capsule staining, as well as non-invasive optical fiber illumination, were performed on all eyes. No intraoperative or postoperative complications were noted. Mean corrected distance visual acuity(logMAR) improved from 1.24±0.17 to 0.73±0.22. Post-phaco intraocular pressure was maintained between 13 to 20 mm Hg in all cases throughout the follow-up period. Mean endothelial cell density decreased from 2258.42±205.94 to 1906.25±174.23 cells/mm2. Phacoemulsification and IOL implantation are safe and valid in eyes with mild to moderate corneal opacities after DALK and coexisting cataracts when assisted with anterior capsule staining and non-invasive optical fiber illumination.

Recurrent interface abscess secondary to Acanthamoeba keratitis treated by deep anterior lamellar keratoplasty

Dear Sir,I am Dr. Yan-Long Bi, from the Department of Ophthalmology of the Tongji Hospital affiliated to Tongji University School of Medicine, Shanghai, China. I write to present a case report of recurrent amoebic corneal abscess

Use of a handheld slit beam intraoperatively to assist in big bubble formation during deep anterior lamellar keratoplasty

Deep anterior lamellar keratoplasty(DALK)is preferred over conventional penetrating keratoplasty(PKP)for the treatment of anterior corneal opacities or ectasias due to decreased risk of endothelial rejection.However,DALK remains surgically challenging,largely due to challenges associated with achieving consistent pneumo-dissection of posterior stroma from the underlying pre-Descemet’s or Descemet’s membrane(DM).Air must be injected at sufficient depth in the corneal stroma in order to achieve successful pneumo-dissection,but advancing a needle too deep into the cornea can lead to perforation of DM.We describe here a novel technique using a handheld slit lamp(Eidolon model 510L,Eidolon Optical LLC,Natick,MA,USA)to assist in creation of the big-bubble in DALK surgery.Use of a handheld slit beam intraoperatively is a safe,relatively inexpensive,and effective technique for increasing the success of big-bubble formation in DALK procedures.

Graft rejection after deep anterior lamellar keratoplasty in fellow eye in macular corneal dystrophy: a case report

Because of the low incidence of immunological rejection,deep anterior lamellar keratoplasty(DALK)is currently the preferred treatment for macular corneal dystrophy(MCD).However,there were few reports about whether the consistent results were obtained when performing DALK in both eyes for MCD,especially when the corneal grafts were taken from different donors.Also,there were few reports about whether the stromal graft rejection occurred typically in both eyes in MCD with DALK.This case may represent the first report of an unusual and misleading manifestation of stromal graft rejection after uneventful DALK with big bubble technique in the fellow eye in MCD.A 32-year-old healthy man with MCD underwent bilateral uneventful DALK with a big bubble technique in the left eye in January and the right eye in July,the corneal grafts were taken from different donors.There was an atypical allograft rejection that occurred in the right eye and none in the left eye;although a timely diagnosis of graft rejection revealed following aqueous determination,it could not be reversed and underwent PK finally.The purpose of this case report is to illustrate the identification of atypical allograft rejection after DALK in the fellow eye,the significance of aqueous detection in the diagnosis of graft rejection,the choosing of grafts,and the timing of bilateral corneal transplantation in patients with MCD.

Long-term comparison of full-bed deep anterior lamellar keratoplasty and penetrating keratoplasty in treating keratoconus

Objective: To compare postoperative outcomes of full-bed deep anterior lamellar keratoplasty (DALK) with penetrating keratoplasty (PK) in treating keratoconus. Methods: Seventy-five eyes of 64 patients who received full-bed DALK and 52 eyes of 51 patients who received PK between June 2000 and August 2010 were included in this retrospective study. Full-bed DALK was performed using Yao's hooking-detaching technique. PK was performed using a standard technique. Intraoperative and postoperative complications, visual acuity, rejection, graft survival, endothelial cell density, corneal sensation recovery, and re-innervation were compared between the two groups. Results: A best correct visual acuity of 0.5 or better was achieved in 90.7% of eyes after full-bed DALK and in 92.3% of eyes after PK (P=0.75). By the fifth postoperative year, graft endothelial cell loss reached 34.6% in the PK group vs. 13.9% in the full-bed DALK group (P<0.001). There were no statistical differences in corneal sensitivity recovery or corneal re-innervation between the groups (P>0.05). Intraoperative microperforation occurred in seven out of 75 (9.3%) eyes with a temporally postoperative double anterior chamber in two eyes in the full-bed DALK group. Postoperative complications in the PK vs. the full-bed DALK groups respectively were: rejection (7.7% vs. 0%, P=0.015), high intraocular pressure (IOP) (46.2% vs. 1.3%, P<0.001), secondary glaucoma (9.6% vs. 0%, P=0.006), complicated cataract (19.2% vs. 0%, P<0.001), and wound dehiscence (9.6% vs. 0%, P=0.006). Conclusions: Both full-bed DALK and PK can offer long-term satisfactory visual outcomes for keratoconus. Graft rejection, secondary glaucoma, complicated cataracts, and constant endothelial cell loss were observed in eyes only after PK.

Refractive outcome of keratoconus treated by big-bubble deep anterior lamellar keratoplasty in pediatric patients: two-year follow-up comparison between mechanical trephine and femtosecond laser assisted techniques

Background:To evaluate refractive outcome 24 months after Deep Anterior Lamellar Keratoplasty(DALK)in pediatric patients by comparing results achieved using mechanical trephine and femtosecond laser.Methods:Twenty eyes of 20 patients affected by keratoconus were evaluated.To perform big-bubble DALK,10 eyes(Group 1;mean age 11.2±2.2 years)were subjected to the Hessburg-Barron mechanical trephine and the remaining 10 eyes(Group 2;mean age 11.3±3.1 years)to a 150 kHz femtosecond laser that performed mushroom incisions.Preoperative thinnest point in the corneal thickness map and K readings were measured by the Sirius Scheimpflug camera.We also evaluated corrected distance visual acuity(CDVA)as logMAR value using spectacles,spherical equivalent and refractive astigmatism.Results:Mean preoperative thinnest point and pre-and post-operative K readings did not show significant difference(P>0.05)between the two groups.CDVA,spherical equivalent and refractive astigmatism were respectively,0.14±0.08 logMAR and 0.13±0.10 logMAR(P=0.8),−4.2±1.1 D and−2.8±1.2 D(P=0.03),4.4±2.0 D and 3.6±1.2 D(P=0.4)in Groups 1 and 2.All DALK procedures were uneventful.Conclusion:Our findings suggest that femtosecond laser compared to mechanical trephine could significantly reduce the spherical equivalent amount in pediatric big-bubble DALK.

Peripheral deep anterior lamellar keratoplasty using a cryopreserved donor cornea for Terrien's marginal degeneration

Objective： To evaluate the clinical efficacy of peripheral deep anterior lamellar keratoplasty （DALK） using a cryopreserved donor cornea for Terrien＇s marginal degeneration （TMD）. Methods： Thirty-one eyes of 27 patients with TMD underwent peripheral DALK using cryopreserved donor corneas, According to the distance between the inner edge of the lesion and the limbus, a ring-shaped or D-shaped DALK was performed. All grafts were stored at -20 ℃. Cryopreserved comeoscleral rims were prepared for ring-shaped grafts and cryopreserved whole eyeballs were prepared for D-shaped grafts. The general conditions, intraoperative performance, postoperative corneal reconstruc- tion, astigmatism, best corrected visual acuity （BCVA）, and various complications were analyzed. Results： Ring-shaped DALK was performed in 28 eyes and D-shaped DALK was performed in 3 eyes. Postoperative follow-up time was （28.4±24.8） months. There was evidence of inflammation before surgery in 12 eyes （38.7%） and intraoper- ative perforation occurred in 13 eyes （41.9%）. The corneal structures of all eyes were reconstructed. Postoperative astigmatism and BCVA showed improvement （both P=0.00） except for cases that underwent D-shaped DALK. Ten eyes （32.2%） developed transient ocular hypertension and one eye （3.2%） developed secondary glaucoma. No pri- mary disease recurrence or corneal allograft rejection was observed. Conclusions： Peripheral DALK for TMD using cryopreserved donor tissue is an effective technique that eliminates rejection and extends the use of donor eyes. Inflammatory history or intraoperative perforation has no adverse effect on graft recovery. However, D-shaped DALK did not achieve good visual outcomes.

Assessments of tear meniscus height, tear film thickness, and corneal epithelial thickness after deep anterior lamellar keratoplasty

Objective： To assess the lower tear meniscus height（LTMH）, central tear film thickness（CTFT）, and central corneal epithelial thickness（CCET） after deep anterior lamellar keratoplasty（DALK）. Methods： This was a retrospective cross-sectional study of 20 patients who had DALK in one eye over a three-month period. LTMH, CTFT, and CCET of the operated eyes and the unoperated fellow eyes were measured using high-definition optical coherence tomography（HD-OCT）. Correlations between three OCT assessments and age, time following surgery, graft size, bed size, and the number of residual sutures were analyzed. Results： Compared to patients with keratoconus, patients with other corneal conditions had significantly higher CCET in the fellow eye（P=0.024）. For all patients, CCET in the operated eye was significantly negatively correlated with the number of residual sutures（R=-0.579, P=0.008）, and was significantly positively correlated with time following surgery（R=0.636, P=0.003）. In the fellow eye, a significant positive correlation was found between age and CCET（R=0.551, P=0.012）, and a significant negative correlation between age and CTFT（R=-0.491, P=0.028）. LTMH was found to be significantly correlated between operated and fellow eyes（R=0.554, P=0.011）. There was no significant correlation between LTMH and age, bed/graft size, time following surgery, or residual sutures（all possible correlations, P0.05）. Conclusions： Patients with keratoconus tend to have a thinner central corneal epithelium. Corneal epithelium keeps regenerating over time after DALK. DALK did not induce a significant change in tear volume compared with the fellow eye. Postoperative tear function might depend on an individual＇s general condition, rather than on age, gender, bed/graft size, time following surgery, or residual sutures.

Effects of corneal thickness distribution and apex position on postoperative refractive status after full-bed deep anterior lamellar keratoplasty

Objective： To investigate the effects of corneal thickness distribution and apex position on postoperative refractive status after full-bed deep anterior lamellar keratoplasty （FBDALK）. Methods： This is a retrospective analysis of patients who were diagnosed with advanced keratoconus between 2011 and 2014 in our hospital. The base of the cone in all patients did not exceed the central cornea at a 6-mm range. The FBDALK was performed by a same surgeon. All patients had a complete corneal suture removal and the follow-up records were intact. Patients who had graft-bed misalignment or who were complicated with a cataract or glaucoma were excluded. Uncorrected visual acuity （UCVA）, best spectacle corrected visual acuity （BSCVA）, and Pentacam examination data were recorded at two years postoperatively. The recorded data included the superior-inferior （S-I） and nasal-temporal （N-T） corneal thickness differences in 2, 4, 6, and 8 mm diameter concentric circles with the corneal apex as the center （S-I2 mm, S-14 mm, S-I6mm,, S-I8mm, N-T2mm, N-T4 mm, N-T6 mm, and N-T8 mm）, the linear, X-axis, and Y-axis distance between the corneal pupillary center and the cornea apex, total corneal astigmatism at a zone of 3 mm diameter from the corneal apex （TA3 mm）, the astigmatic vector values J0 and J4s, and the corneal total higher-order aberration for 3 and 6 mm pupil diameters （HOA3 mm and HOA6mm）. Statistical analysis was performed by SPSS 15.0. Results： A total of 47 eyes of 46 patients met the criteria and were included in this study. The mean follow-up time was （28±7） months. The mean UCVA was 0.45±0.23 （IogMAR） （MAR： minimum angle of resolution） and the mean BSCVA was 0.19±0.15 （IogMAR）, which were all sig- nificantly positively correlated with postoperative TA3 mm and HOA3 turn. The mean S-I corneal thickness differences were （44.62±37.74） IJm, and the mean N-T was （38.57±32.29） pm. S-12 mm was significantly positively correlated with J0 （r=0.31）, J45 （r=0.42）, HOA3 mm （r=0.37）, and HOA6 mm （r=0.48）. S-14 mm and S-Is mm were significantly positively corre- lated with HOA3 mm （t=0.30, t=0.40） and HOA6 mm （r=0.46, r=0.35）. The X-axis distance between corneal pupillary center and corneal apex was significantly positively correlated with J45 （r=0.29）. Conclusions： In patients with ad- vanced keratoconus after FBDALK, the unevenly distributed thickness at corneal pupillary area and the misalignment of corneal apex and pupillary center might cause significant regular and irregular astigmatism, which affected the postoperative visual quality.

深板层角膜移植与穿透性角膜移植治疗基质角膜营养不良预后的比较

背景:基质角膜营养不良的传统手术治疗方式为穿透性角膜移植,近年来越来越多的医生开始考虑使用深板层角膜移植治疗基质角膜营养不良。目前国内对比穿透性角膜移植和深板层角膜移植治疗基质角膜营养不良的研究少有报道。目的:比较深板层角膜移植和穿透性角膜移植治疗基质角膜营养不良的疗效。方法:选择2000年1月至2018年1月北部战区总医院收治的基质角膜营养不良患者57例(57眼),男18例,女39例,平均年龄(52.9±20.0)岁,按照手术治疗方式分为深板层角膜移植组(n=21)、穿性角膜移植组(n=36),术后随访观察最佳矫正视力、角膜内皮细胞密度、角膜植片透明度、术中及术后并发症、原病复发情况。结果与结论:①两组患者术后1,3,6,12个月的视力均高于术前(P<0.05),两组间术后不同时间点的视力比较差异无显著性意义(P>0.05);随着术后时间的延长,两组患者角膜内皮细胞密度逐渐降低,穿透性角膜移植组患者术后6,12个月的角膜内皮细胞密度年丢失率均高于深板层角膜移植组(P<0.05);两组患者术后12个月的角膜植片透明率比较差异无显著性意义(P>0.05);②深板层角膜移植组有6例出现并发症,穿透性角膜移植组有14例出现并发症,57例患者术后12个月内均无复发,两组患者术后5年的复发率比较差异无显著性意义(P>0.05),穿透性角膜移植组和深板层角膜移植组术后5年的移植物存活率分别为83%和86%,组间比较差异无显著性意义(P>0.05);③结果表明,基质角膜营养不良的治疗可考虑使用深板层角膜移植替代一部分穿透性角膜移植。