Dr. Shreya Thatte
Introduction
Diseases affecting the cornea are a major cause of preventable blindness worldwide.1However, there are numerous etiologies threatening the structural integrity of the anterior segment and this requires immediate attention and intervention before addressing the visual impairment. Such corneal pathologies which tend to involve the sclera always remain a challenge to manage. Removing the diseased part of cornea and sclera and replacing it with a stronger healthy donor tissue thus providing support to the globe and reconstructing anterior segment structures to anatomically and physiologically near normal ,remains the mainstay of management in such cases. If left untreated can progress to other significant ocular comorbidities and phthisis resulting in permanent loss of vision.
Many terms such as penetrating therapeutic or tectonic keratoplasty or penetrating Sclerokeratoplasty have been introduced since the evolution of keratoplasty. All of these can be encompassed into a single terminology – “Reconstructive keratoplasty”. Barraquer has defined it as the use of a corneal graft, of varying size, shape and position , to end or improve those treatment resistant diseases of the cornea that result in dissolution of tissue and the production of anatomic or structural defects that are incompatiblewith continued survival of theglobe.2
Sclerokeratoplasty poses a higher risk than a routine keratoplasty.Primary disease with concurrent distorted anatomy of the anterior segment and use of a larger graft increases chances of gravepotential complications like graft rejection, graft failure, secondary glaucoma making secondary procedures mandatory so as to obtain a desirable outcome.Therefore it requires a great deal from the surgeon to provide tectonic as well as optical results.
This study was undertaken to observe primary outcome of tectonic i.e. to achieve globe stabilization with a secondary optical outcome i.e. visual rehabilitationafter reconstructive keratoplasty in cases of severely damaged cornea involving surrounding sclera.
Material and Methods:
This prospective interventional study included 60 eyes of 60 patients with severely diseased corneoscleral tissue inpathological conditionslikeinfective sclerokeratitis or perforation, anterior staphyloma, ectasia,dry eye, peripheral ulcer and sterile corneoscleral melt.
Preoperative:
The patients were segregated into 2 groups i.e. Group A: Infective pathology and Group B: Non-infective pathology.They underwent series of routine ocular examination and special ocular investigations wherever possible. Perception of light was present in 100% cases. Beyond this, visual acuity was sequentially assessed with respect to projection of rays, hand movement and finger counting measured in feet.After a thorough slit lamp examination, preoperativephotographs were taken for documentation. Intraocular pressure (IOP) was assessed digitally by a single observer and B scan was done in patients of both the groups except in open globe cases.
Samples of conjunctival swab and corneal scraping were retrievedas and when necessary for culture and sensitivity.All patients in group B excluding those with an open globe underwent ultrasound biomicroscopy (UBM). Group B patients suggestive of systemic involvement were subjected to special investigations other than the routinely done in order to determine a causative factor.
The patients and close relatives were counselled about the procedure, associated complications, guarded prognosis, the requirement for subsequent procedures and the necessity of an excellent compliance and a regular follow up for a long period post-operatively and a written informed consent was taken.
The local treatment for each case was individualized according to the need of the case.IV mannitol 20% 1 gm per kg body weight was given preoperatively on the day of surgery to reduce the intraoperative IOP.Penetrating sclerokeratoplasty was planned and all the patients were operated upon by a single surgeon at the same institute under general anaesthesia in patients with open globe whereas local anaesthesia with sedation in all the other cases.
Intraoperative:
After doing conjunctival peritomy,the devitalized host tissue was gently marked using a hand-held trephine or Vernier calipers(in eyes with extreme scleral involvement) and manually excised using Castroviejo’s scissors till the summit of healthy tissue.A 9.5 – 10 mm diameter corneoscleral donor graft was sized half mm larger while >10 mm diameter graft was kept 1 mm larger than the host defect andwas procured either with a corneal punch or freehand depending on its size.Suturing in these patients requires a special mention.Apposition in corneo-scleral or sclero-scleral graft host junction is not that good compared to corneo-corneal junction, the reasons being variable depths and uneven surface of corneal and scleral tissue,irregular edges of sclera and dissimilar scleral rigidity.Hence,varying the suture tension and length and changing the direction of suture was done as and when required.Many modifications such as pupillary membrane removal,thorough A/C wash, synechiolysis,intracameral antibiotic injection, iris reconstruction, cataract removal, vitrectomywere carried out simultaneously during keratoplasty as per the pathological condition of the eye.
Postoperative:
All the patients were then subjected to appropriate postoperative management according to etiology and followed up for a period of 1 – 5 years. In group A cases, we refrained from administeringcorticosteroids in any form for a minimum of 10 days post-operatively. Systemic and topical antibiotics were employed depending upon the culture-sensitivity report.These patients were frequently reexamined for signs of recurrence and topical prednisolone acetate was started thrice a day only in cleaneyes after 10 days of surgery under very close observation, stopped if untoward finding noted, then againstarted after a trial instillation with the dosing frequency gradually escalated to six times daily only after the 15th postoperative day.In group B cases, topical steroids six times daily supplemented by systemic steroids 1 mg/kg body weight/per day were initiated from the first post-operative day.During follow –up, all patients were assessed forgraft clarity,visual acuity,IOP, suture related complications,signs suggestive of persistent inflammation,graft rejection,recurrence of disease and other complications and appropriate medical and surgical interventions were done as and when required.
Observation and Results:
Table 1
| Age groups (Years) | Number of patients (n=60) | Percentage | Number of Males | Number of females |
| 5 – 25 | 9 | 15 % | 4 | 5 |
| 26 – 50 | 34 | 56.66 % | 12 | 22 |
| 50 – 70 | 17 | 28.34 % | 6 | 11 |
Our study incorporated 60 patients of all age groupswith 38(63.34%) being females and 22(36.66%) males, the age and gender distribution as seen in table 1.
Table 2
| Etiology | Number of patients (n=60) | Percentage |
| Group A | ||
| Severe necrotizing refractory infectious sclerokeratitis | 18 | 30 % |
| Large perforation | 15 | 25 % |
| Group B | ||
| Sclero-corneal melt | 6 | 10 % |
| Anterior staphyloma | 10 | 16.67 % |
| Peripheral ulcer | 7 | 11.66 % |
| Ectasia | 4 | 6.67 % |
The etiological classification of these patients who underwent reconstructive keratoplasty is represented in table 2. Large perforationsimply a size of more than 8 mm diameter and were due to grievous corneal infection.Out of the six corneoscleral melts, four had rheumatoid arthritis while two had severe dry eye disease associated with meibomitis.Mooren’s ulcer led to peripheral ulceration in seven patients.Ectasia was due to corneal thinning post healed ulcer in two eyes and pellucid marginal degeneration in other two.The eyes with corneal thinning were earlier planned for lamellar keratoplasty but Descemet’s membrane perforation occurred after air injection hence had to be converted.
Table 3 shows categorization of patients based on donor graft size and maximum extent of scleral excision. In the marginal excision group limbus to limbus corneal involvement was present and scleral excision was required only for marginal refining.Scleral involvement of less than 1 mm was observed in maximum number of patients.Sclerectomy performed in each patient was differential and quite variable limited to diseased quadrants only and not circumferentially symmetrical makingthe graft eccentric in many patients.
| Table 3 | |||
| Donor graft size (in mm) | Maximum extent of scleral excision | Number of patients (n=60) | Percentage |
| 9.5 to 10.5 | Marginal excision | 14 | 23.33 % |
| > 10.5 to 11.5 | < 1 mm | 25 | 41.67 % |
| Upto 12 | 1 – 2 mm | 21 | 35 % |
The endothelial cell count of the donorgraft transplanted in a few cases especially of anterior staphyloma was as low as 1500 cells/mm2 depending upon availability at that time keeping in mind the sole purpose of globe stabilization.Otherwise the cell count in maximum patients was more than 2000 cells/mm2.
Table 4 illustrates the modifications or additional procedures done during surgery in 47 cases (78.34 %) overall as per case scenario in order to enhance the desired results.In majority patients more than one modification had to be done simultaneously in a single case.
| Table 4 | ||
| Modifications during surgery | Number of patients (n=60) | Percentage |
| Cataract extraction with IOL | 4 | 6.67 % |
| Cataract extraction without IOL with anterior vitrectomy | 5 | 8.33 % |
| Release of anterior/ posterior synechiae | 38 | 63.33 % |
| Thorough anterior chamber wash | 33 | 55 % |
| Pupillary membrane removal | 31 | 51.67 % |
| Intracameral injection of antibiotic | 33 | 55 % |
| Tarsorrhaphy | 1 | 1.67 % |
| Reconstruction of iris | 2 | 3.33 % |
Surgical outcome was assessed individually in each of these patients separately in terms of tectonic(primary) as well as optical(secondary)as depicted in tables 5,6 and 7. The eye could not be salvaged and had to be eviscerated in 5 patients of group Abecause of recurrence of infectionrecalcitrant to medical management and extending to the posterior segment.
| Table 5 | ||
| Primary outcome
(Tectonic) |
Number of patients (n=60) | Percentage |
| Achieved | 55 | 91.67 % |
| Not achieved | 5 | 8.33 % |
The optical outcome portrays the status of graft whether healthy and clear or hazy and failed. Out of the 55 cases(91.67%) who had achieved globe integrity i.e. primary outcome,11 eyes(20%) landed up in graft failure and underwent regrafting.
The remaining 44 eyes(80%) who had fulfilled optical i.e. secondary outcome comprised of 9 patients with a clear graft, favourable visual gain and without any ocular comorbidity and the rest 35 patients with a clear graft i.e. optically successful but still poor visual recovery due to grave perioperative complications such as aphakia, cataract formation, secondary glaucoma, vitreous haemorrhage, retinal and choroidal detachment.Thus overall we had 9 patients(16.36%) with no secondary procedure required and 46 patients(83.64%) who underwent some procedure. These 9 patients belonged to group B with the etiology being ectasia(2 eyes,3.63%),peripheral ulcer(4 eyes,7.27%) and sclerocorneal melt(3 eyes,5.45%).
The abovecomplicationsencountered after surgery in the 46 patients,hampering the vision directlyandcompelling the use of secondary proceduresare given in table 8a.The choroidal detachment was observed in 3 cases(5.45%) which resolved with systemic steroids and no surgical intervention was required.
Moreover, many complications faced in immediatepostoperative period significant in directly influencing the graft survival and indirectly the vision like shallowing of anterior chamber,reappearance of hypopyon,reformation of synechiae or pupillary membrane,suture related complications such as loose suture, infiltrates, early vascularization and graft rejection demanded an urgent intervention as shown in table 8b.Early graft rejection in 7 cases of group A noticed within 2 weeks of surgery was successfully managed with intravenous methylprednisolone(IV MPS) 1 gm per day for 3 days followed by oral prednisolone 1mg/kg body weight tapered gradually and by increasing frequency of topical steroids.
Table 6
| Optical outcome
(Graft clarity) |
Number of patients (n=55) | Percentage |
| Achieved | 44 | 80 % |
| Not achieved | 11 | 20 % |
Table 7
| Number of patients (n=55) | Percentage | Secondary procedure done | |
| Clear graft with no ocular comorbidity | 9 | 16.36 % | No |
| Clear graft with ocular comorbidity | 35 | 63.64 % | YES |
| Hazy graft | 11 | 20 % | YES |
Table 8A
| Direct vision threatening grave complications/sequelae | Secondary procedure | Ectasia | Anterior staphyloma | Large perforation | Refractory sclerokeratitis | Peripheral ulcer | Sclerocorneal melt | Total (n=55) | Percentage |
| Complicated Cataract | Cataract surgery | 2 | 2 | 2 | 0 | 3 | 1 | 10 | 18.18 % |
| Aphakia | Secondary IOL | 0 | 1 | 2 | 2 | 0 | 0 | 5 | 9.09 % |
| Secondary glaucoma | Trabeculectomy | 0 | 3 | 3 | 2 | 0 | 1 | 9 | 16.36 % |
| Retinal detachment | RD surgery | 0 | 1 | 4 | 0 | 0 | 1 | 6 | 10.92 % |
| Vitreous haemorrhage/ Vitritis | PPV | 0 | 2 | 0 | 3 | 0 | 0 | 5 | 9.09 % |
| Graft failure | Regrafting | 0 | 1 | 2 | 8 | 0 | 0 | 11 | 20 % |
Table 8B
| Direct graft threatening & Indirect vision threatening complications in all patients | Procedure done | Number of patients (n=55) | Percentage |
| Shallowing of anterior chamber(A/C) | Air injection/additional 1-2 sutures applied at leakage site | 3 | 5.45 % |
| Reappearance of hypopyon | A/C wash & repeat injection of intracameral antibiotic | 5 | 9.09 % |
| Reformation of synechiae | Synechiae release/ subconjunctival steroid injection | 13 | 23.63 % |
| Formation of pupillary membrane | Peeling of membrane/ subconjunctival steroid injection | 8 | 14.55 % |
| Suture – related | Early suture removal | 27 | 49.09 % |
| Early graft rejection | Administration of IV MPS | 7 | 12.73 % |
Table 9
| Final best corrected visual acuity(BCVA) | No. of patients (n=55) | Percentage |
| >6/60 – 6/18 | 22 | 40 % |
| 3/60 – 6/60 | 17 | 30.91 % |
| < 3/60 | 16 | 29.09 % |
Out of the 5 aphakic patients,PCIOL in 1whereas ACIOL and scleral fixated IOL in each of 2 patients were implanted.Indications for vitrectomy included vitreous haemorrhage in 2 eyes and severe refractoryvitritis in 3 eyes.Trabeculectomy was done under mitomycin-C in all 9 cases of secondary glaucoma . However, rise in IOP persisted in one patient of staphylomawith 360 degree scleral involvement along with large diameter graft ( 10.5 mm) even after trabeculectomy so glaucoma drainage device(GDD)was implanted thus resulting in IOPcontrol.Regrafting was done in 11 cases(20 %)of graft failure which included 1 (1.82 %) patient of anterior staphyloma in group B while 10 from group Acomprising of recurrence of infection in 3 eyes(5.45 %) and non responding graft rejection in 5 eyes(9.09 %)and 2 eyes(3.64 %) of infective sclerokeratitis and perforation respectively.
Table 9 illustrates the final best corrected visual acuity(BCVA).BCVA of more than 6/60 on Snellen’s chart was recorded in 22 patients (40%) out of which the maximum visual acuity(V/A)of 6/18 was seen in 7 patients(12.72%) of group B. BCVA of 3/60-6/60 was observed in 17 patients (30.91%). The suboptimal visual recovery of < 3/60 seen in overall 16 eyes (29.09%) is attributable to the refractory posterior segment pathology in 11 eyes despite all measures and failed regraft in 5 eyes.The lowest vision noted was hand movement close to face present in 9 patients(16.37%) of group A.
DISCUSSION:
Sclerokeratoplasty or Reconstructive keratoplasty is a radical and holistic approach to salvage the eye. Sclerokeratoplasty was first described by Girard in 1956 who reported a clear graft seen in 50% of patients.3
In our study, the 60 patients(60 eyes) who underwent reconstructive keratoplasty, belonged to all age groups from 5 – 67 years with more number of females than males(Table 1) as in age-matched studies by Taylor et al4(36 patients,50 eyes) and Hirst and Lee13 (23 eyes).
Reconstructive keratoplasty in our study was performed for diverse indications(Table 2) as done by Taylor et al4 ,Hirst and Lee13 and Skeens HM et al14 (35 eyes) but with etiological differences compared to our study.Unlike our study, Panda et al5,10 did two comparative studies between sclerokeratoplasty and penetrating keratoplasty in 20 cases of staphyloma and refractory corneal ulcer each and Jonas et al8 reported outcome of a double comparative study in 60 patients (60 eyes) with perforated or predescemetal corneal ulcers treated by two different emergency procedures and further comparing it with elective keratoplasty.Stephen M et al 12 and Kirkness et al15 have mentionedtheir results in just one or two indications while Enrique de la et al6 ,Esquenazi et al7 ,Radoslaw R et al9 ,BarbanyM et al11have presented case reports.
All keratoplasties in this study were penetrating with graft size more than 9.5 mm(Table 3) from which 46(76.67%) were corneoscleral grafts i.e. with a rim of sclera.The asymmetrical width of the encircling scleral rim in our study had an impact on the centricity of the graft making many grafts eccentric but this deemed necessary as we aimed for excising only the necrosed tissue and preserving the healthy part. Other authors12,14,15 have also used a similar graft size.Unlike our study, Taylor et al4 did 35 penetrating, 15 lamellar and just 16 of 35 eyes received a graft sized more than 9.5 mm out of which only 2 had a rim of sclera with no mention about the centricity of graft while Hirst et al13 used graft sizes within 11-14 mm range.
Though the major portion of reconstructive keratoplasty contributes to globe preservation, there are multiple other small yet considerable issues happening because of the primary disease and the procedure per se which need to be dealt with concomitantly for favourable results.Studies4,13 in the past have briefly described this.We would like to stress upon the numerous additional surgical steps/procedures (Table 4) done in our study for thesesmaller issues.
1) Initially addressing the ocular surface,total conjunctival peritomy alongwith vigorous removal of diseased conjunctiva was done for good scleral exposure.This helped in identifying the extent of non-viable corneoscleral tissue and facilitated in fashioning a recipient bed void of all the devitalized tissue thus obtaining a clean healthy graft host junction(sclero-scleral/ corneo-scleral) free from conjunctiva hence preventing early vascularization causing rejection.
2) We followed the principle of ‘saving as much viable tissue as possible’ in view of restoring an anterior segment anatomy close to normal. Gentle superficial separation of the iris tissue from the cornea using swab stick or scissors in a strongly adhered iris in cases of broad anterior synechiae especially in staphyloma was done with iris reconstruction(if needed).
3) In infected cases, the fibrinous exudative membrane from the anterior chamber(A/C) and angle was peeledoff under extreme precautions using a non-traumatizing fine forceps without causing damage to deeper iris tissue and lens capsule together with posterior synechiolysis.
4) Subsequently, meticulous wash of the A/C, its angle and even the ciliary sulcus was done andbroad spectrum antibiotic (preservative free moxifloxacin 0.5%) was injectedintracamerally especially in infected cases to alleviate disease recurrence.
5) Utmost care was taken to avert spontaneous extrusion of lens and vitreous intraoperatively by avoiding any excess pressure on globe in a deeply sedated patient and with IV mannitol 20% 100cc infused during surgery if needed.
6) Coexistent cataract extraction and IOL implantation with thorough anterior vitrectomy in eyes with lens extrusion was performed to completely eliminate its adverse effects in A/C.
7) All sutures were applied in interrupted manner with knots buried in the donor tissue. 8) The importance of tarsorrhaphy is highlighted in eyes with incomplete lid closure so as to shield the ocular surface.This was done in our study in just a single patient of large corneal perforation due to neuroparalytic infectious keratitis as a sequela of Hansen’s disease.Routinely done prophylactic tarsorrhaphy only to promote epithelialisation has been recommended by other authors4,13,17.
All these smaller steps when done correctly translate into a prolonged graft survival with controlled recurrence and improved success rate.
Studies10,11 on sclerokeratoplasty have reported lower incidence of reinfection. A very high proportion of prognosis after sclerokeratoplasty in infective sclerokeratitis is determined by many important preoperative factors such as timely consultation by the patient, condition of the eye at the time of presentation and well timed commencement of an effective treatment regime after diagnosing the pathology accurately. Identifying the offending pathogen, its drug sensitivity and modifying the medical treatment accordingly goes a long way in sustaining a recurrence free status after transplant. The organisms isolated in all 33 patients of group A were fungi(8),gram positive cocci(6),methicillin resistant staphylococcus aureus(4),pseudomonas(6) while no growth was reported in 9 eyes.
Reinfection in graft was observed in three eyes(5.45%) after sclerokeratoplasty which were then subjected to regrafting.The 5 eyes which had to be eviscerated in this study had a preoperative chronic, very severe, therapy resistant fulminating infection due to an unidentified organism with an ongoing history of 4 – 6 weeks rendering them non-salvagable despite all measures.The duration between sclerokeratoplasty and evisceration ranged from 4-8 weeks.Hirst et al13 in their study reported this duration range from 0-80 months and performed enucleation/evisceration in 9 of 23 eyes.
Performing sclerokeratoplasty in actively inflamed eyes using a large diameter graft comes with its own share of pros and cons apart from that of a routinely done elective penetrating keratoplasty (graft size < 9mm).Though a larger graft ensures complete extermination of the unwanted pathological tissue, surgeon cannot judge as to what microscopic structures are being damaged internally particularly the angle anatomy thus anticipated to have increased chances of secondary glaucoma which was seen in 9 patients in our study predominantly in eyes with staphyloma,perforation and infection. Studies5,10reported no significant association of secondary glaucoma
with sclerokeratoplasty when compared to keratoplasty. Cobo et al 17 showed use of angle support sutures for preservation of angle anatomy.Burk et al16 and Jonas et al8 depicted the technique of lamellar preparation of scleral bed for preventing this damage,but this was not possible in our study with majority cases showing full thickness scleral involvement. In the study done by Hirst and Lee13,13 of 23 patients developed glaucoma from which 6 required surgery.Alternative surgeries have also been described by Taylor et al4. Similarly, we resorted to trabeculectomy in all patients except one patient of staphyloma having total aniridia who was later implanted with GDD after a failed trabeculectomy.
Additionally,larger grafts are known to be associated with an elevated incidence of graft rejection1.A large graft (corneoscleral graft) compromises the immune privileged status maintained by a corneal graft when sutured into an avascular clear cornea of the recipient as seen in keratoplasty18,19. Studies have mentioned cyclosporine as a topical adjunct to steroids for immunosuppression in sclerokeratoplasty14,16 and was administered by us in group B cases with autoimmune pathology. Early graft rejection in cases of group A can be attributed to the delayed commencement of topical steroids in view of preventing disease recurrence. Thus, learning to maintain this balance between antibiotic-steroid combination is highly mandatory in such cases.
The patients with non-responding graft rejection were non-compliant to treatment and had a delay in seeking medical help thus augmenting the already increased risk of a large graft.The other compounding factor for rejection in a few cases could be the utilization of donor cornea available at the earliest even the one with lower endothelialcell countcontemplating the primary aim of globe preservation and avoiding phthisis. Surprisingly, this has never been taken into consideration by other similar studies.
Large grafts are present within close vicinity of limbal vasculature and hence suture related complications expected to be more common are also of prime concern in stimulating graft rejection. Jonas et al8 reported that frequencies of suture loosening and immunologic graft reactions was worse for the patients operated on corneal ulcers than for the patients undergoing elective keratoplasty for inactive corneal scars. In our study,suture related problems were observed in 27 eyes and early suture removal was done in such eyes i.e. even before 6 weeks following sclerokeratoplasty as also done by Panda20.Previously done similar studies4,13 have not mentioned these complications.
In our study, epithelial defect or delayed epithelial healing if noted was readily managed by increasing frequency of lubricating eye drops, marginal debridement or use of bandage contact lens similar to Burk et al16 without subjecting the patients to tarsorrhaphy.However,persistent epithelial defects were not observed.Panda et al5,10 in their trials showed no significant difference in the frequency of epithelial defects.Panda20 in their study found out that to obtain healthy stem cells, freshly preserved corneoscleral tissue is preferred over long-term glycerin-preserved corneas or intermediate term M-K-preserved cornea but this is not always feasible with sclerokeratoplasty being an emergency procedure.
The commonly encountered vision threatening complications in this study i.e.cataract (18.18%), secondary glaucoma(16.36%),aphakia(9.09%),graft rejection(12.73%),graft failure(20%) are commensurate with the studies4,5,10,13-15 done previously. Retinal detachment (10.92%) as a complication has been reported by only Hirst and Lee13.
The tectonic outcome in 91.67% patients, optical outcome i.e. clear graft in 80% eyes achieved in our study alongwith the visual outcome is comparable to results reported by other authors4,12-15.
The fact that reconstructive sclerokeratoplasty is an emergency necessary measure only to restore the anatomic integrity of the globe in a hopeless situation where enucleation and evisceration seemed to be the only option in the past cannot be ignored and demands a well-informed patient,meticulous unique approach,close careful observation,proper decision making and excellent compliance to treatment and follow-up.Though it does not suffice in restoring vision, subsequent additional procedures can always be incorporated in the treatment paradigm.
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