DR. PINKAL SHIROYA

DR. REVATHI RAJARAMAN, Dr.ARJUN VELAYUDHAN NAIR

Semi Final

Abstract

A Retrospective study of patients less than 18 years who underwent DALK for Keratoconus. 227 eyes of 186 patients were included. The outcomes like best corrected visual acuity, keratometry, epithelial defect healing time and its complications. The mean UCVA and BSCVA was improved to 0.51±0.39 and 0.49±0.33 LogMAR units respectively. The mean keratometry decreased 51.51± 5.82D postoperatively. The epithelial healing time was 4.25±6.23 days. Suture removal was initiated by 7.81±7.66 months and completed by 29.26±19.70 months. The complication encountered were DM perforation 15.39%, double anterior chamber 3 cases, vascularization 13.2%, secondary glaucoma 14.9%, cataract 5.7%, graft infections,9.3%, graft rejection 6.6% and graft melt 1.3%.

CONCLUSION

DALK though challenging in paediatric cornea, provides good optical & refractive outcome with long-term graft survival.

Full Text  

To analyses the long-term outcome of deep anterior lamellar keratoplasty in pediatric keratoconus

Abstract
Aim and objective

Aim and objective

To analyses the long-term outcome of deep anterior lamellar keratoplasty in pediatric keratoconus.

Method and materials

This is retrospective study of patients less than 18 years who underwent DALK for Keratoconus from February 2008 to December 2009. 227 eyes of 186 patients were included. Preoperative corneal evaluation was done. The outcomes like best corrected visual acuity, keratometry, epithelial defect healing time and its complications. The mean UCVA and BSCVA was improved to 0.51+0.39 and 0.49+0.33 LogMAR units(p<0.001) respectively.

The mean keratometry decreased 51.51± 5.82D postoperatively. The epithelial healing time was 4.25+6.23 days. Suture removal was initiated at 7.81+7.66 months and completed by 29.26 +19.70 months. The complication encountered were DM perforation 15.39%, double anterior chamber 3 cases, vascularization 13.2%, secondary glaucoma 14.9%, cataract 5.7%, graft infections 9.3%, graft rejection 6.6%, graft melt 1.3%.

Conclusion

DALK though challenging in paediatric cornea, provides good optical & refractive outcome with long-term graft survival.

Introduction:

Keratoconus an ectatic corneal disease characterizes by progressive stromal thinning, irregular astigmatism and defective vision. It starts at puberty and progress rapidly to an advanced stage. It poses a burden to society as it affects quality of life, social and educational development. Hence early diagnosis recognition of progression and timely intervention with collagen cross-linking or keratoplasty. At a times, severe ocular allergy when associated hastens progression. Studies on pediatric keratoconus suggest that at the time of diagnosis, 22.8% are at advanced stages and 88% progress.

In children keratoplasty can be challenging due to lower scleral rigidity, the need for recurrent general anesthesia, the tendency for early suture related problems and infections and graft rejection due to a stronger immune system. Deep Anterior Lamellar Keratoplasty (DALK) has become the preferred procedure for keratoconus since it retains structural integrity and reduces the chance of endothelial rejection. However, the procedure is technically complex even in adult corneas. This study analyses the feasibility of DALK in pediatric keratoconus, long term visual and functional outcomes and complications.

Methods :

This is a retrospective analysis of interventional case series. Informed consent was obtained from patients as well as from Institutional Review Board to review and share the data. Medical records of all keratoconus patients less than 18 years of age who underwent DALK for keratoconus were analyzed. . Preoperative corneal status by slitslit-lamp examination, topography and visual status by uncorrectedand best-corrected visual acuity (UCVA, BCVA), presence of local or systemic comorbidities were noted.

Keratoplasty, preferably DALK was planned in children with advanced keratoconus, with inadequate best-corrected spectacle visual acuity.Penetrating keratoplasty was done mostly for post hydrops corneas. All surgeries were done under general anesthesia. Big-bubble was attempted in all eyes. If it failed, the procedure was completed with either manual layer by layer dissection or hydro-dissection. A 0.25 mm oversized donor buttons were sutured with minimum of 16 interrupted sutures with 10 0’nylon. Post-operatively topical antibiotics were given for 2 weeks, prednisolone acetate started four times and gradually tapered to one time daily by 6 months. It was replaced by loteprednol by 12 months or earlier in steroid responders. Cyclosporine A 0.1% was also added and maintained.

If the sutures became loose before 3 months, they were replaced as per wound integrity. Suture removal was done in batches by around 12 months if the graft-host junction scar is dense enough. Surgical details like the achievement of big bubble, need for manual or hydrodissection were noted. Incidence of Descemet’s membrane perforation and whether it was converted to penetrating keratoplasty were also noted. Post-operatively problems in wound healing including epithelial healing, early loosening of sutures, need for pneumopexy for detached Descemet’s membrane, time to start and end suture removal, stable refraction and visual acuity was noted. Complications like glaucoma and its management, vascularization, infection, graft rejection and their outcome also were analyzed.

Results

227 eyes of 186 patients who underwent DALK for keratoconus from February 2008 to December 2019 were evaluated retrospectively. The mean age group was 14.87±2.68 (minimum 6 years to a maximum of 18 years). 70.5% (n=160) eyes were males and 29.5% (n=67) were females, 50.7% (n=115) eyes were OD and 49.3% (n=112) were OS. On examination 35.7% (n=81) eye had scar on preop evaluation and 1.3% (n=3) had deep scars in ASOCT. Vernal keratoconjunctivitis (VKC) was seen in 39.2% of eyes(n=89). Patients were followed up for a period of 47.63 ± 31.66 months eyes (Min 2months to Max 130 months).

The preoperative uncorrected visual acuity UCVA was 1.27±0.27 logmar units (n=227), preoperative bestcorrected spectacle visual acuity was 0.67±0.31 and best-corrected contact lens acuity was 0.24±0.26 (n=181). Postoperative uncorrected visual acuity was 0.76±0.29 logmar units (n=225) and best-corrected spectacle visual acuity was 0.18±0.16 (n=222). On comparing the means the uncorrected visual acuity showed a significant improvement of 0.51±0.39 logmar units (p<0.001), bestcorrected visual acuity also showed a significant decrease by 0.49±0.33 log Mar units (p<0.001).

The preoperative refraction showed an average spherical value of 8.49 ± 5.68D and cylindrical value of 4.97 ± 1.63D. Preoperative topography showed a mean keratometric maximum (Kmax) of 62.67 ± 7.78D (min=43.20 and max=97.80), and simulated keratometry (Sim k) had a mean of -7.76 ± 3.43D. Postoperative period refraction showed a mean spherical value of -2.93 ± 1.80D and cylinder of -2.78 ± 2.17D. Postoperative topography had Kmax of 51.51±5.82D and Sim k of 4.88 ± 2.86D.
On comparing, the Mean withT-test significant decrease in mean spherical power by 5.17±5.29D (p<0.001) and mean cylindrical value by 2.37 ± 2.64D (p<0.001) was noted. Topography also showed a significant decrease in mean K max by 9.56 ± 8.19D (p<0.001) and Sim K by 3.35 ± 4.86D (p<0.001).

The surgical technique of DALK majority of cases Big Bubble was achieved 66.1% (n=150), Manual Dissection was done in 21.6% (n=49) and Hydro dissection in 11.9% (n=27). Intraoperatively 15% (n=34) of cases had perforation and 11% (n=25) required rebubbling.
The time required for the epithelial defect to heal was 4.25 ± 6.23 days. Suture replacement following DALK was required in 21.6% (n=49) and was done within a mean period of 3.87 ± 2.54 weeks.
Suture removal following surgery was initiated at a mean period of 7.81 ± 7.66 months (n=203) and was completed within a mean period of 29.26 ± 19.70 months (n=141).

Complications in the post-operative period, Vascularisation was seen in 13.2% (n=30), Graft Infections in 9.3% (n=21), Graft Rejection in 6.6% (n=15), Graft Melt in 1.3% (n=3) which were managed conservatively. Glaucoma in 29.5% (n=67) out of these 46.26% (n=31) required anti glaucoma medication and 4.4% (n=3) required selective laser trabeculoplasty. Evaluating contralateral eye of these patients 49.8% (n=113) cases underwent corneal collagen cross linkage, 11% (n=25) underwent DALK & 2.57% (n=6) cases were converted to penetrating keratoplasty.

Subgroup Analysis of Complications

Rejection:

Most cases were stromal rejection. The mean duration of rejection incidence was 13.38 ± 7.68 months.

Infection

Most cases are suture infiltrate. The commonest organism cultured is Step. Pneumonia. One case had a recurrence of shield ulcer with infiltrate. Cases included patients with Down’s syndrome as comorbidity.

Cataract

13(5.7%) cases developed cataract during follow up period. The most common type was posterior subcapsular cataract. 3 patients underwent cataract surgery during follow up period. Among the patients who developed cataract 3 cases (23.08% among those developing cataracts) had Descemet’s perforation at the time of surgery, out of which 2 cases (15% among those developing cataracts) required rebubbling in the postoperative period.

Suture Replacement:

49 cases required replacement in the immediate post-operative period. Among those who required replacement 18 cases had vernal keratoconjunctivitis as comorbidity. Among the keratoconus patients with VKC undergoing DALK 20.22% will require early suture replacement.

Miscellaneous:

3 cases developed intact DM detachment and required intracameral Air injection. One eye developed Urrets Zavalia syndrome after pneumopexy. Two cases of non-healing epithelial defect required botox injection, the third case required AMG and botox.

Discussion

Pediatric keratoconus is associated with good visual recovery as well as graft survival among other congenital or acquired traumatic indications after keratoplasty. Penetrating Keratoplasty in children is reported to be challenging due to anatomical factors like lower rigidity, narrower palpebral fissure and crowded anterior segment. Moreover, endothelial rejection which can lead to graft failure is expected more in children due to a stronger immune system. Most of the studies on keratoplasty in children analyze both penetrating keratoplasty and DALK for mixed indications. Our study reports the safety of doing DALK exclusively in pediatric keratoconus and its short and long term results.

Deep Anterior Lamellar Keratoplasty is the procedure of choice for keratoplasty in adults because it preserves anatomical stability as well as eliminates endothelial rejection. Aurora et al reported 80% of Big Bubble achievement and Feizi shows 75% achievement which is much more as compared to our report having 66 % achievement because of varying levels of experience among the surgeons. Elbaz et al suggested manual dissection as a safe method in children to avoid conversion to penetrating keratoplasty. Though DM perforation was noted in 15% of cases, we could complete the procedure in all but 3 cases of post hydrops corneas.

Feizi et al reported the visual acuity was comparable between big-bubble and manual dissection in pediatric as well as in adult keratoconus. Patel et al reported BCVA in 86% after PK and Felzi reported in 84% post DALK.We have noticed a significant improvement in both uncorrected and best spectaclecorrected visual acuity as well as topographic parameters.
The post-operative double anterior chamber was noted in 11%, even with intact DM in 3 cases. All these cases were resolved with pneumopexy, with one eye developing Urrets Zavalia syndrome.

Javadi and Han et al Immune graft rejection was reported to be higher in incidence post-penetrating keratoplasty than after DALK for keratoconus, in adults. Moreover, in our report, Graft Rejection was sub-epithelial or stromal 6.6 %, sparing endothelium, with good recovery. Whereas Javadi et al, Feizi et al reported 9.1 – 23.8 %.
Glaucoma was seen in 29 % of our cases, which is higher than the reported 13 – 18% by Feizi et al . Though it was controlled by medication in most of the cases, 4.4% needed intervention in the form of selective laser trabeculoplasty.

Arora et al, Feizi et al, also noted early suture loosening and replacement, suture tract vascularization, suture infections. In our study vernal keratoconjunctivitis as a comorbidity was associated with delayed epithelial healing, vascularisation affecting overall graft survival. Vkc with shield ulcer was noted in our study, plaque removal and early initiation of steroids preserved graft clarity in
these cases. Similar cases & interventions were adapted by Arora et al.

Cataract was noted in 5.7% of eyes, predominantly posterior subcapsular. Cataract in our study was less than 14 – 25% reported by Javedi et al in ost DALK adults with keratoconus.
Limitations of the study: This is a retrospective analysis with the attendant shortcomings in the availability of some data. We have included cases with follow-ups as early as 2 months to as late as 130 months. However, we wanted to show the possibility of early postoperative problems, which are expected more in children as well as long-term outcomes.

Conclusion :

Our analysis showed that DALK can be done safely in pediatric keratoconus, with good visual recovery and graft survival. DALK can be associated with unique technique related complications like DM perforation and double anterior chamber which need to be addressed in time. Vernal keratoconjunctivitisis a co-morbidity can be associated with healing and suture related. These children need to be closely monitored for complications like glaucoma and cataract also.

Results:

TABLE 1

	N	Mean	SD	SE
PRE_UCVA	221	1.275	0.269	0.018
POST_UCVA	219	0.76	0.299	0.02
PRE_BCSVA	219	0.675	0.312	0.021
POST_BCVA	216	0.183	0.160	0.011

TABLE 2

N	Mean	SD	SE
PRE_SPH	150	-8.643	5.701	0.465
POST_SPH	135	-2.917	1.841	0.158
PRE_CYLN	200	-4.959	1.598	0.113
POST_CYLN	140	-2.775	2.181	0.184

TABLE 3

N	Mean	SD	SE
PRE_KMAX	149	62.654	7.738	0.634
POST_KMAX	106	51.501	5.852	0.568
PRE_SIMK	146	7.719	3.447	0.285
POST_SIMK	104	4.897	2.888	0.283

Twelve eyes of 12 keratoconus patients and fifteen eyes of 15 PCG patients were analysed on ASOCT. The mean age of the patients with keratoconus at the time of OCT examination was 21.2 ± 6.4 years (range 14-36 years) whereas that of PCG was 16.1 ± 4.9 years (9-25 years) (p<0.001). The disease duration was significantly higher in KC eyes (21.2 ± 6.4 years) than that of the PCG eyes (14.8 ± 8.1 years) The mean highest baseline IOP documented was 15.43 ± 2.59 mm Hg and 31.81 ± 6.11 mm Hg in the keratoconus and PCG group respectively. The mean spherical equivalent was -5.50±4.81 DS (-14.00 to -2.25 DS) and -3.25±4.78 DS (-10.00 to +3.00 DS) in keratoconus and PCG group respectively.

The mean keratometry and corneal astigmatism was significantly higher in the KC group (56.1 ± 11.5 D and 6.00 ± 5.50 DC). The mean horizontal corneal diameter was 11.93 ± 0.39 mm and 13.61 ± 0.86 mm in keratoconus and PCG eyes respectively. 66.7% of PCG eyes and 41.7% of KC eyes undergoing ASOCT presented with clear cornea. Mild to moderate to severe corneal haze was present in the remaining eyes. ASOCT revealed significantly thinner corneas in the KC group (394.8 ± 70.1 μm) in comparison to the PCG group (526.7 ± 56.5 μm). Additionally, ASOCT also showed significantly thinner DM-PDL complex inside (47.1 ± 25.5 μm) the areas of hydrops in keratoconus group when compared to the PCG group (77.2 ± 26.2 μm) (p<0.01).

Similar findings were noted outside the areas of hydrops (15.6 ± 4.3 μm) in keratoconus group in comparison to the PCG group (20.4 ± 5.5 μm) (p<0.01). Both the groups showed the DM-PDL complex as two separate hyper-reflective lines with translucent space in between, giving it a “double membrane” appearance. The DM was found to be globally thickened in all scans of PCG eyes with intracameral protuberances of varying sizes and shapes in the areas of Haab’s striae.

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