Penetrating keratoplasty for keratoconus in Down's syndrome

Down syndrome: a review of ocular manifestations

Down syndrome is the most common genetically mediated intellectual disability. Although many physiologic and pathologic features of Down syndrome are discussed at length in the literature, the ocular manifestations of Down syndrome have seldom been discussed in a comprehensive fashion. Given that Down syndrome has ocular manifestations from the front to the back of the eye, it is important for physicians to become familiar with these manifestations, especially given the prevalence of Down syndrome. This review aims to discuss the varied ophthalmologic manifestations of Down syndrome – including strabismus, amblyopia, nystagmus, accommodation deficits, nasolacrimal duct obstruction, keratoconus, optic nerve pathology, neoplastic disease, and retinal pathology – to facilitate better care and visual outcomes in this important patient population.

Performing corneal crosslinking under local anaesthesia in patients with Down syndrome

Purpose

To report on the ability to perform corneal crosslinking (CXL) under local anaesthesia for the treatment of keratoconus in patients with Down syndrome.

Methods

Nine eyes of seven patients with both keratoconus and Down syndrome were scheduled for an epithelium-off CXL procedure under local anaesthesia. Exclusion criteria were a corneal thickness under 400 µm and the presence of corneal scars. A standardized clinical decision tool was used to estimate patient cooperation and the likelihood for a successful procedure under local rather than general anaesthesia.

Results

In seven eyes, the CXL was completed successfully. The treatment was aborted in two eyes due to insufficient corneal thickness (<400 µm) prior to ultraviolet-A irradiation, even after employing hypoosmolar riboflavin. No adverse events occurred post-operatively, except for one case of delayed epithelial healing (23 days).

Conclusions

With a proper patient selection, CXL under local anaesthesia can be achieved in patients with Down syndrome.

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.

Long-term Graft Survival in Patients with Down Syndrome after Penetrating Keratoplasty

PURPOSE

To determine graft survival and long-term visual outcome after penetrating keratoplasty (PK) for keratoconus in patients with Down syndrome.

METHODS

The records of all patients with Down syndrome who received PK by the same provider were reviewed. A retrospective analysis was performed to determine long-term graft survival, incidence of graft failure, and complication rate.

RESULTS

Twenty-one PKs were performed on 18 eyes of 13 patients with Down syndrome with keratoconus. Three repeat PKs were performed for secondary graft failure. All 18 eyes had clear grafts at the most recent examination. Follow-up ranged from 4 to 88 months, with a mean of 34.9 months. The average age of patients was 42 years, with a range of 20 to 63 years. Preoperative visual acuity ranged from 20/160 to count fingers. Postoperatively, visual acuity was objectively measurable in 12 eyes of 8 patients and ranged from 20/30 to 20/200, with a mean of 20/60. Broken sutures and difficulties with unsedated suture removal complicated postoperative care in some patients.

CONCLUSION

Clear grafts and improvements in visual acuity can be obtained after PK in patients with Down syndrome, but consideration must be given to careful postoperative care by health care providers and home support personnel.

Patterns of rejection after deep lamellar keratoplasty

PURPOSE

To describe 7 patients with keratoconus who underwent graft rejection after deep lamellar keratoplasty (DLK).

DESIGN

Retrospective case series and literature review.

PARTICIPANTS

Seven patients who underwent DLK for keratoconus between 1997 and 2001. These cases were compared with a previously reported case series of DLK for keratoconus between 1994 and 2001.

METHODS

The clinical records of patients with rejection after DLK for keratoconus were examined to obtain details of the surgery, the interval to the rejection episode and its treatment, best-corrected visual acuity (BCVA), and presence of potential risk factors for rejection. The clinical features and course of rejection were compared with reports of corneal graft rejection in the literature. Patient characteristics were compared with the reported series of patients who had DLK for keratoconus.

MAIN OUTCOME MEASURES

Final BCVA and number, type, and features of rejection episodes.

RESULTS

The mean age was 28 years, with a median follow-up of 40 months after DLK. Rejection occurred between 3 and 41 months postoperatively. Four patients were atopic, 4 had a penetrating keratoplasty in the fellow eye, and 1 had deep stromal vessels in the host cornea. Isolated epithelial rejection occurred in 1 patient and stromal rejection in 3 cases, and there were 3 cases of mixed stromal and epithelial rejection. Topical steroid therapy led to reversal of rejection in 5 cases. Two patients had progressive vascularization with graft failure and poor vision. The median final BCVA was 6/9 (range, 6/6-6/36).

CONCLUSIONS

Deep lamellar keratoplasty avoids the risk of endothelial rejection, but epithelial or stromal rejection may still occur. Recognition and appropriate treatment are needed to prevent graft failure with subsequent visual loss.

Comparison of deep lamellar keratoplasty and penetrating keratoplasty in patients with keratoconus

OBJECTIVE

To compare the therapeutic outcomes after deep lamellar keratoplasty (DLK) and penetrating keratoplasty (PK) in patients with keratoconus.

DESIGN

Retrospective case-control study.

PARTICIPANTS

We reviewed the clinical notes of 47 patients diagnosed clinically with keratoconus who had received DLK (26 eyes of 25 patients) or PK (25 eyes of 22 patients) at Moorfields Eye Hospital or the Royal Shrewsbury Hospital between 1994 and 2001. The patients in the 2 groups were matched for severity of their keratoconus by preoperative visual acuity.

METHODS

Deep lamellar keratoplasty was performed with the Melles technique in 7 eyes and the technique described by Sugita and Kondo in 19 eyes. Penetrating keratoplasty was performed with a standard technique using a Hessburg-Barron trephine. A single continuous 16-bite 10-0 nylon suture was placed and adjusted in both groups.

MAIN OUTCOME MEASURES

Best-corrected visual acuity (BCVA), refractive results, surgical techniques for DLK, and complication rates were analyzed.

RESULTS

The 25 patients with keratoconus who underwent DLK had a mean age of 32.6 years and a median follow-up of 28 months. The mean age of the 22 patients who underwent PK for keratoconus was 34 years. This group was followed up for a median time of 55 months. The median final BCVA of patients in the DLK group was 6/9 and in the PK group 6/6 (no statistical significance). The median result for the final spherical equivalent power in both groups was mild myopia, although the DLK group had more myopia, and the median astigmatism was less than 5.00 diopters cylinder for both groups. Complication rates were similar for DLK and PK, although the nature of the complications varied.

CONCLUSIONS

Penetrating keratoplasty is no longer an automatic choice for the surgical treatment for keratoconus; DLK seems to be a safe alternative. Best-corrected visual acuity, refractive results, and complication rates are similar after DLK and PK. Deep lamellar keratoplasty is more technically challenging but allows the risk of endothelial rejection to be avoided and may reduce the risk of late endothelial failure.

Corneal topography after ocular rubbing

PURPOSE

To examine the immediate effect of ocular rubbing on corneal topography.

METHODS

Corneal topography and analysis were performed before, immediately after, and 5 minutes after eyelid rubbing in 29 volunteers without ocular disease.

RESULTS

The surface regularity index increased from a baseline of 0.24 to 0.91 ( p< 0.0001) immediately after rubbing and returned to baseline after 5 minutes. The surface asymmetry index increased from 0.27 to 0.89 ( p= 0.0018) immediately after rubbing. There was a small amount of astigmatism induced immediately by rubbing (0.5 diopter) ( p= 0.01).

CONCLUSIONS

Ocular rubbing should be avoided prior to standard corneal topography. The increased surface regularity index may reflect the alterations of the tear film and/or the molding of the corneal surface.

Corneal grafting for keratoconus in mentally retarded patients

PURPOSE

To compare the results of penetrating and non-penetrating corneal grafting procedures in mentally retarded keratoconus patients.

METHODS

In the years 1974-2000 41 mentally retarded patients with keratoconus (33 with Down syndrome) were operated with corneal grafting. Mean age at operation was 36.7+/-10.8 years. Three different surgical procedures were used (no randomization): penetrating keratoplasty (n=16), lamellar keratoplasty (n=5) and epikeratophakia (n=20). In a retrospective study, the non-penetrating procedures (lamellar keratoplasty and epikeratophakia) were compared to the penetrating keratoplasties with regard to graft survival and frequency of serious complications. Mean follow-up time of all grafting procedures was 80+/-58 months.

RESULTS

All cases of serious complications (irreversible rejection, wound leakage or perforation) occurred in the penetrating keratoplasty group (p=0.0005). Older age at operation (p=0.011) adversely influenced the frequency of serious complications. Overall five-year survival was 74.9%. Graft survival was not related to surgical procedure, but rather to age at operation (poorer survival in older age, p=0.012) and degree of retardation (poorer survival in patients with more severe retardation, p=0.051).

CONCLUSIONS

Because of the safety and low frequency of complications, epikeratophakia is recommended as the grafting procedure of choice in the majority of mentally retarded with keratoconus. In selected cases (good cooperation, age < or =40 years, and a good peripheral corneal thickness) penetrating keratoplasty may be performed, which, if uncomplicated, often will give better functional/optical results.

Corneal myxoma associated with keratoconus and Down's syndrome

PURPOSE

Primary myxoma of the cornea is extremely rare. Until now, only four primary corneal myxomas were reported in the literature, whereas secondary involvement of the cornea by conjunctival and limbal tumors is much more common.

METHODS

We report an additional case in a 26-year-old woman with keratoconus and Down's syndrome. Excision of the corneal mass was performed by penetrating keratoplasty. Histochemical, immunohistochemistry, and ultrastructural studies were used to obtain a definitive diagnosis.

RESULTS

The tumor exhibited the characteristic histologic features of myxoma. The tumor cells showed immunoreactivity for vimentin but not for S-100 protein, epithelial membrane antigen, CAM 5.2, HHF-35, or muscle-specific actin. Ultrastructural features were fibroblast-like or stellate cells with cytoplasm containing abundant, rough reticulum and dilated cisternae. No recurrence was observed 36 months after penetrating keratoplasty.

CONCLUSION

This is only the fifth report of such an occurrence. Although the coexistence of myxoma in Down's syndrome with keratoconus is described here for the first time, the differential diagnosis of apparently evident acute hydrops on clinical inspection should not rule out the possibility of a corneal myxoma. Histologic analysis should therefore be performed.

Penetrating keratoplasty in the mentally retarded

Penetrating keratoplasty is infrequently performed in the mentally retarded due to the high risk of serious post-operative complications, in particular wound rupture and severe inflammation of the graft. Graft survival is hindered by the patient's tendency for eye rubbing and possibly self-inflicted injury. Adequate nursing support is essential to ensure strict compliance with post-operative treatment. A retrospective study of corneal graft outcomes in mentally retarded patients was undertaken to assess graft survival, visual rehabilitation, post-operative complications and the influence on social behaviour. Six cases of penetrating keratoplasty performed in mentally retarded patients by one surgeon are presented. A continuous 10-0 nylon suture was employed in all cases. In 2 cases surgery was undertaken following perforation of the globe in patients with Down's syndrome. The grafts were retained in all cases and 2 patients achieved reasonably good acuity, although formal visual acuity assessment in these patients is limited. Penetrating keratoplasty in mentally retarded patients is a potentially hazardous procedure and patients require close supervision and good support care. This series demonstrates that relatively successful outcomes can be obtained in some mentally retarded patients.

The results of penetrating keratoplasty for keratoconus

At the Department of Ophthalmology, University Hospital in Lund, Sweden, keratoconus is the most common indication for penetrating keratoplasty. We studied 77 keratoplasties performed on keratoconic eyes between 1989-1991. Postoperative corrected visual acuity was better than or equal to 0.5 in 65 eyes (84.4%), and 30 eyes (39%) had visual acuity of 1.0. The mean postoperative astigmatism was 3.75 D with a range of 0-12.5 D. Eight patients underwent relaxing incision with satisfactory results in 6 patients. Graft rejection was observed in 6 eyes (7.8%). The most serious complication seen in our group of patients was a retrocorneal fibrous membrane that developed in one patient.

Ocular findings in 55 patients with Down's syndrome

Fifty-five patients with Down's syndrome were examined to evaluate the characteristics and frequency of ocular findings. Of these patients, 29 (52.7%) were hypermetropes, 7 (12.7%) were emmetropes, and 7 (12.7%) were myopes; astigmatism of more than 3.00 diopters was present in 7(12.7%) patients. Strabismus was observed in 12 (21.8%) patients. All but one of these 12 patients also had esotropia. Congenital nasolacrimal duct obstruction was present in 12 subjects (21.8%). Blepharitis was found in 19 (34.5%) cases. Nystagmus occurred in 7 (12.7%) patients. Brushfield spots were detected in only 20 (36.3%) of the patients and were more common in light-colored irides. Lens opacities were diagnosed in 11 (20%) patients, and two underwent successful cataract surgery. On fundus examination, an increased number of retinal vessels crossing the optic nerve head was detected in 21 (38.1%) cases. One of the patients had a retinal detachment. Significant but correctable ocular problems are present in patients with Down's syndrome and may interfere with the quality of life of the patient and with binocular vision. Surgical intervention may be needed for strabismus and for cataracts.

Acute corneal hydrops in keratoconus

PURPOSE

To determine the clinical factors associated with the development of acute corneal hydrops and its subsequent outcome.

METHODS

The authors identified 147 eyes (124 patients) with acute hydrops from a database of 5242 eyes (2723 patients) with keratoconus. They compared the clinical features of patients in whom hydrops developed with unaffected patients and assessed the progression to penetrating keratoplasty by actuarial methods.

RESULTS

Patients in whom acute hydrops developed tended to be younger males who had advanced corneal ectasia and a poor corrected Snellen visual acuity at the diagnosis of their keratoconus (P < 0.001). Acute hydrops also was more common in the presence of severe allergic eye disease (P < 0.001). The development of hydrops was a very significant risk factor for subsequently receiving a penetrating keratoplasty (P < 0.00001) and at the end of the study period 87 (59%) of the 147 eyes had surgery for visual rehabilitation. These eyes had a greater rate of graft rejection than eyes grafted without hydrops (P = 0.02). After resolution of the hydrops, 46 of the 60 unoperated eyes had been refitted with contact lenses, of which 28 (61%) achieved a Snellen visual acuity of 20/40 or better, although a better visual acuity often was present in the contralateral eye. Microbial keratitis developed in two of these eyes after refitting.

CONCLUSIONS

Although a penetrating keratoplasty often is indicated for visual rehabilitation after acute corneal hydrops, there is an increased rate of rejection. Only a minority of eyes were re-established in contact lenses after resolution of hydrops, but some patients achieved a functional level of visual acuity such that the procedure could be delayed or avoided.

Surgical treatment of corneal pathology in patients with Down's syndrome

Keratoconus is a major cause of blindness in patients with Down's syndrome. A retrospective study of 30 corneal grafts for keratoconus in these patients revealed a 5-year graft survival of 67%. Postoperative trauma and/or infection was the main cause for graft failure. Conditions that should be met before the indication for corneal transplantation in a patient with Down's syndrome are formulated as a result of 15 years experience with that patient population. In appropriate cases, corneal transplantation may undoubtedly improve the quality of life in these patients.

Epikeratophakia for keratoconus in mentally retarded patients. The use of fresh, free-hand made lamellar grafts

Epikeratophakia for keratoconus was done in 11 mentally retarded patients, using fresh, free-hand made lamellar grafts. The mean follow-up period was 31.5 months. The grafts remained clear and well adapted in 7 cases (63.6%). Necrosis of the lower part of the graft occurred in 3 eyes (27.3%), and was probably caused by persisting epithelial defects. Only one of these grafts had to be removed. Despite concurrent eye diseases, such as cataract and possible amblyopia, an improved overall visual function was reported in 5 of the 11 patients (45.5%). No vision-threatening complications related to the epikeratophakia surgery was found.