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Oversized corneal grafts for corneal opacities with iridocorneal adhesions
Oversized Corneal Grafts for Corneal Opacities with Iridocorneal Adhesions Rasik B. Vajpayee, MBBS, MS, Tanuj Dada, MD, Manotosh Ray, MD, Radhika Tandon, MD, FRCOphth, Anita Sethi, MD, FRCS, Kiran Turaka, MD Objective: To evaluate the efficacy of 1-mm oversized corneal grafts in patients with acquired corneal opacities and extensive peripheral iridocorneal adhesions. Design: Prospective noncomparative case series. Participants: Twenty patients (20 eyes) aged 15 years or older with unilateral or bilateral corneal opacification and a shallow anterior chamber. Intervention: Penetrating keratoplasty was performed with donor corneal buttons oversized by 1 mm. Main Outcome Measures: The various parameters evaluated were visual acuity, graft clarity, keratometry, anterior chamber depth, intraocular pressure, and spherical equivalent refraction 12 months after surgery. Results: The keratoplasties were performed in 15 eyes with a corneo-iridic scar after infectious keratitis (75%) and 5 eyes with failed graft (25%). At the final follow-up, a clear graft was achieved in 17 eyes (85%), and 14 eyes (70%) achieved a best-corrected visual acuity of 6/12 or better. Three of the grafts failed because of rejection. The average keratometry was 44.1 ⫾ 1.0 diopters (D), and the mean spherical equivalent was ⫺3.23 ⫾ 2.86 D. The oversized grafts provided a mean anterior chamber depth of 2.36 ⫾ 0.42 mm, and the mean intraocular pressure at the 12 month follow-up was 16.38 ⫾ 2.09 mmHg. Conclusions: Corneal grafts oversized by 1 mm provide adequate anterior chamber depth and reduce the risk of peripheral anterior synechiae and secondary glaucoma in patients with corneal opacities and extensive peripheral iridocorneal adhesions. Ophthalmology 2001;108:2026 –2028 © 2001 by the American Academy of Ophthalmology. Corneal transplant surgery is one of the most successful organ transplant surgeries in the world. Functional results are, however, limited by complications such as graft rejection, high postoperative astigmatism, and secondary glaucoma. Although complications like graft rejection and postoperative astigmatism have been observed to occur in all parts of the world, we have been observing a high incidence of peripheral anterior synechiae, secondary glaucoma, and graft failure in our country, where corneo-iridic scars after infectious keratitis constitute the major indication for corneal grafting surgery. Peripheral anterior synechiae are more frequent in patients with a preexisting shallow anterior chamber, especially in eyes with corneo-iridic scars, and development of these synechiae often results in secondary glaucoma and other problems leading to graft failure.1,2 We had been routinely using 0.5-mm oversized corneal grafts in such eyes but noticed high rates of peripheral anterior synechiae (PAS) and secondary glaucoma. There are several advantages of using an oversized donor corneal button in
Originally received: December 5, 2000. Accepted: May 15, 2001. Manuscript no. 200846. From the Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. Presented in part as a poster at the annual meeting of the American Academy of Ophthalmology, Dallas, Texas, October 2000. Reprint requests to Rasik B. Vajpayee, MBBS, MS, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, Ansari Nagar, New Delhi-110 209, India.
2026
© 2001 by the American Academy of Ophthalmology Published by Elsevier Science Inc.
corneal grafting surgery. These include better wound healing, increased anterior chamber depth, fewer PAS, and a decreased incidence of postkeratoplasty glaucoma.3–5 We recently reported good results with corneal grafts oversized by 1 mm in pediatric patients.6 To evaluate the role of grafts oversized by 1 mm in adults with corneo-iridic scars and extensive PAS, we undertook this prospective study.
Materials and Methods Twenty eyes of 20 patients, aged 15 years or older, were enrolled from the cornea service of our hospital. Eyes with corneo-iridic scars and failed grafts with flat or shallow anterior chambers with extensive PAS were included in this study. Eyes with posterior segment pathology, uncontrolled glaucoma (intraocular pressure [IOP] ⬎ 21 mmHg on one topical medication), and subnormal electrophysiologic tests (visual evoked potential and electroretinogram) were excluded. Initial evaluation included a detailed history, visual acuity, slit-lamp biomicroscopy, measurement of IOP, electrophysiologic examinations (visual evoked potential and electroretinogram), and posterior segment evaluation by ultrasonography. All patients underwent penetrating keratoplasty using donor corneal buttons oversized by 1 mm. Donor corneas were preserved in McCarey-Kaufman medium and used within 24 hours. Donor corneas were punched from the endothelial side using a Teflon block for support. Castroviejo disposable trephines were used to cut the donor and host corneas. While cutting the host cornea, the trephine blade was used to make an approximately 3/4-depth cut after proper centration. The anterior chamber was entered with a ISSN 0161-6420/01/$–see front matter PII S0161-6420(01)00772-2
Vajpayee et al 䡠 Oversized Corneal Grafts Table 1. Graft Outcome at 12 Months (n ⫽ 20) Clear grafts Keratometry (diopters) Anterior chamber depth (mm) Intraocular pressure (mmHg) Astigmatism (diopters) Spherical equivalent (diopters) Visual acuity ⬎ 6/18
17 (85%) 44.10 ⫾ 0.99 2.36 ⫾ 0.42 16.38 ⫾ 2.09 2.38 ⫾ 0.53 ⫺3.23 ⫾ 2.86 14 (70%)
disposable blade, and the cut was completed with curved Vannas scissors. In eyes with an adherent leukoma, a debulking technique with lamellar dissection2 was used initially and then the anterior chamber was entered in an attempt to preserve as much iris tissue as possible. Pupilloplasty, synechiolysis, and anterior segment reconstruction were performed if necessary. Grafts were secured using interrupted 10-0 monofilament nylon sutures. All patients were treated with topical steroids (1% prednisolone acetate), antibiotics (0.3% ciprofloxacin), ocular lubricants, and antiglaucoma medications (0.5% timolol maleate) after surgery. Prednisolone acetate drops were gradually tapered from an initial frequency of 4 hourly in the first week, to 2 times daily up to the sixth month after surgery. All patients were switched over to low-concentration steroids (0.01% dexamethasone) after 6 months. Topical antibiotics and antiglaucoma treatment were discontinued between 2 and 3 weeks after the surgery. No systemic therapy was given except in two cases of high-risk grafts in which systemic prednisolone (1 mg/kg/day) was used. High-risk grafts were defined as grafts with deep vascularization in two or more quadrants and failed grafts because of immunologic rejection. All patients were evaluated at 1 week, 4 weeks, 3 months, 6 months, and 12 months after surgery. Visual acuity, IOP, graft clarity, angle structures, keratometry, and anterior chamber depth were recorded. IOP was measured with the Goldmann applanation tonometer, gonioscopy was done with the Goldmann single-mirror contact lens, and the central anterior chamber depth was measured with A scan ultrasonography. Clear grafts were defined as optically clear corneas with no Descemet’s folds or edema and full visibility of the iris and lens. Graft rejection was diagnosed when there was graft edema without any apparent clinical reason after an initial period of a clear graft for at least 10 days. Loose, vascularized, or infiltrated sutures were removed when necessary. Selective suture removal was done after 6 months to control postkeratoplasty astigmatism if necessary. The final refraction was performed at the 12 month follow-up.
Results Of the 20 patients enrolled in our study, 14 were males and 6 were females, with a mean age of 46.8 ⫾ 17.4 years (range, 15–75 years). The major indications for corneal grafting were corneoiridic scar caused by infectious keratitis in 15 eyes (75%) and failed grafts in 5 eyes (25%). The donor trephination graft size was 8.5 mm in 16 eyes (80%) and 9.0 mm in 4 eyes (20%). Pupilloplasty and anterior segment reconstruction were required in 12 eyes, and goniosynechiolysis was performed in all of the eyes. Mean preoperative IOP recorded was 17.07 ⫾ 2.77 mmHg. IOP was normal throughout the study. The mean IOPs recorded at the fourth week, third month, sixth month and 1 year were 17.78 ⫾ 1.70, 16.94 ⫾ 1.70, 16.73 ⫾ 2.23, and 16.38 ⫾ 2.09 mmHg, respectively. A clear graft was achieved in 85% of eyes at the final follow-up examination (Table 1). Three grafts failed because of graft rejection despite adequate treatment. The preoperative visual
Table 2. Best-corrected Visual Acuity at 12 Months Visual Acuity
No.
Percentage
6/6–6/9 6/12–6/18 6/24–6/60 ⬍6/60
5 9 3 3
25 45 15 15
acuity was less than finger counting in all cases. Fourteen eyes (70%) achieved a best-corrected visual acuity of 6/18 or better, whereas five eyes had a visual acuity of 6/9 or better (Table 2) at the final follow-up. In the eyes with a clear graft the mean corneal astigmatism was 2.38 ⫾ 0.53 diopters (D), the mean spherical equivalent was ⫺3.23 ⫾ 2.86 D (range, ⫺7 D to ⫹ 4 D) and the average keratometry at the end of 12 months of follow-up was 44.10 ⫾ 0.99 D. The mean anterior chamber depth was 2.36 ⫾ 0.42 mm at the final follow-up examination (Table 1). None of the patients had PAS. The graft– host junction was well apposed, and there was no overriding of the edge of the graft at any time in the postoperative period. Four (20%) patients had an attack of graft rejection. Graft rejection was successfully reversed in one patient, but despite intensive therapy the rejection could not be reversed in three patients. All of these patients had been seen by us 4 to 6 days after symptoms had started. Repeat surgery was planned in these three eyes.
Discussion A corneal button oversized by 0.5 mm is traditionally used for corneal grafting in adults.3–5 Corneal opacification along with iridocorneal adhesions is one of the major indications for corneal grafting in this part of the world, and most of these cases have a shallow anterior chamber preoperatively.1,2 It has been our experience that despite optimal suturing and synechiolysis, many patients with preexisting iridocorneal adhesions have a shallow anterior chamber, PAS, and raised IOP during the postoperative period, which often leads to graft failure. It is hypothesized that the lens–iris diaphragm is located more anteriorly in patients with preoperative iridocorneal adhesions and a shallow anterior chamber.6 In these patients, the floppy iris tissue tends to develop a memory for this abnormal position, and thus synechiae frequently form in the postoperative period.6 Moreover, it is a well-documented fact that corneal buttons cut from the endothelial side are smaller than those cut from the epithelial side.7 Although many surgeons prefer to use 0.5-mm oversized grafts, the problems of shallow anterior chamber and occurrence of PAS may still not be eliminated in many of the patients, especially those with extensive iridocorneal adhesions. We had found that grafts oversized by 1 mm provide an adequate anterior chamber depth and increase the morphologic success of corneal grafting in pediatric eyes.6 Therefore we decided to extrapolate this concept to adults with corneal opacities having iridocorneal adhesions, shallow anterior chamber, and PAS. In this study, 1-mm oversized corneal grafts provided an excellent postoperative anterior chamber depth, and none of our patients had PAS. Weiss and Waring8 have advocated a novel technique for
2027
Ophthalmology Volume 108, Number 11, November 2001 objective evaluation of goniosynechiae during anterior segment reconstruction. They use a dental mirror for assessing the PAS intraoperatively after removing the host corneal button. The synechiolysis is done with an iris sweep/cyclodialysis spatula under direct visualization of the angle by looking into the mirror so that a complete synechial release can be objectively ensured. Waring9 also used the dental mirror along with indentation of the limbus with a muscle hook for better visualization of the goniosynechiae and advocated the use of cellulose sponges, smooth forceps, iris sweep, knife, and scissors for releasing various types of synechiae. Using the aforementioned technique with grafts oversized by 0.25 mm to 0.5 mm in eyes with aphakic/ pseudophakic bullous keratopathy, the authors reported PAS in 10% of the cases at the end of the surgery and in 30% of their cases at a follow-up of 6 to 12 months.10 In comparison, in this study using the grafts oversized by 1 mm, none of the cases were detected to have PAS in the postoperative follow-up period. Postkeratoplasty glaucoma is a common occurrence, with several studies citing an incidence ranging from 18% to 75%.1,3,11 This variation may be in part due to differences in surgical techniques, suture tightness, and the definition of glaucoma. Zimmerman et al12 postulated that interruption of Descemet’s membrane by the incision results in loss of anterior support of the trabecular meshwork and decreased outflow facility, leading to glaucoma. A decrease in outflow facility can be prevented by oversized grafts.13,14 Furthermore, several clinical studies have demonstrated a reduction of early postkeratoplasty IOP rise in oversized versus samesized grafts.3,14 However, all the previous studies used 0.25-mm to 0.5-mm oversized grafts when the incidence of postoperative glaucoma was still significant,3,5 and we had observed a similar trend in our clinical practice. In this study we used 1-mm oversized corneal grafts, and none of our patients recorded raised IOP after surgery. The IOP was controlled and stable throughout the study. In our study, 85% eyes (n ⫽ 17) achieved a clear graft, and 70% (n ⫽ 14) had a best-corrected vision of 6/18 or better at 12 months. The mean spherical equivalent in eyes with successful grafts was ⫺3.23 ⫾ 2.86 D. The myopic shift was caused because of the steepening of the corneal curvature subsequent to the use of oversized grafts. Although our study did not have a control group for comparative evaluation, it was apparent that 1-mm oversized corneal grafts provided good anterior chamber depth and had a lower incidence of both PAS and postoperative glaucoma. Most of our patients maintained excellent graft
2028
clarity, had optimal best-corrected visual acuity, and had good anatomic results after surgery. We therefore recommend the use of grafts oversized by 1 mm in eyes with corneal opacification associated with extensive PAS.
References 1. Vajpayee RB, Taherian K, Honavar SG, Negi A. Anterior synechiolysis after keratoplasty. Ophthalmic Surg 1995;26: 264 – 6. 2. Vajpayee RB, Angra SK, Honavar SG, Taherian K. Protection of the iris by lamellar dissection of corneal layers. A technique in penetrating keratoplasty. Cornea 1994;13:16 –9. 3. Zimmerman T, Oslon R, Waltman S, Kaufman H. Transplant size and elevated intraocular pressure: postkeratoplasty. Arch Ophthalmol 1978;96:2231–3. 4. Foulks GN, Perry HD, Dohlman CH. Oversize corneal donor grafts in penetrating keratoplasty. Ophthalmology 1979;86: 490 – 4. 5. Oslon RJ, Mattingly TP, Waltman SR, Kaufman HE. Refractive variation and donor tissue size in aphakic keratoplasty: a prospective randomized study. Arch Ophthalmol 1979;97: 1480 –1. 6. Vajpayee RB, Ramu M, Panda A, et al. Oversized grafts in children. Ophthalmology 1999;106:829 –32. 7. Olson RJ. Variation in corneal graft size related to trephine technique. Arch Ophthalmol 1979;97:1323–5. 8. Weiss JS, Waring GO III. Dental mirror for goniosynechiolysis during penetrating keratoplasty. Am J Ophthalmol 1985; 100:331–2. 9. Waring GO III. Management of pseudophakic corneal edema with reconstruction of the anterior ocular segment. Arch Ophthalmol 1987;105:709 –15. 10. Waring GO III, Kenyon KR, Gemmill MC. Results of anterior segment reconstruction for aphakic and pseudophakic corneal edema. Ophthalmology 1988;95:836 – 41. 11. Oslon RJ, Kaufman HE. Prognostic factors of intraocular pressure after aphakic keratoplasty. Am J Ophthalmol 1978; 86:510 –5. 12. Zimmerman TJ, Krupin T, Grodzki W, Waltman SR. The effect of suture depth on outflow facility in penetrating keratoplasty. Arch Ophthalmol 1978;96:505– 6. 13. Oslon RJ, Kaufman HE. A mathematical description of causative factors and prevention of elevated intraocular pressure after keratoplasty. Invest Ophthalmol Vis Sci 1977;16:1085– 92. 14. Oslon RJ. Aphakic keratoplasty: determining donor tissue size to avoid elevated intraocular pressure. Arch Ophthalmol 1978; 96:2274 – 6.
Originally received: December 5, 2000. Accepted: May 15, 2001. Manuscript no. 200846. From the Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. Presented in part as a poster at the annual meeting of the American Academy of Ophthalmology, Dallas, Texas, October 2000. Reprint requests to Rasik B. Vajpayee, MBBS, MS, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, Ansari Nagar, New Delhi-110 209, India.
2026
© 2001 by the American Academy of Ophthalmology Published by Elsevier Science Inc.
corneal grafting surgery. These include better wound healing, increased anterior chamber depth, fewer PAS, and a decreased incidence of postkeratoplasty glaucoma.3–5 We recently reported good results with corneal grafts oversized by 1 mm in pediatric patients.6 To evaluate the role of grafts oversized by 1 mm in adults with corneo-iridic scars and extensive PAS, we undertook this prospective study.
Materials and Methods Twenty eyes of 20 patients, aged 15 years or older, were enrolled from the cornea service of our hospital. Eyes with corneo-iridic scars and failed grafts with flat or shallow anterior chambers with extensive PAS were included in this study. Eyes with posterior segment pathology, uncontrolled glaucoma (intraocular pressure [IOP] ⬎ 21 mmHg on one topical medication), and subnormal electrophysiologic tests (visual evoked potential and electroretinogram) were excluded. Initial evaluation included a detailed history, visual acuity, slit-lamp biomicroscopy, measurement of IOP, electrophysiologic examinations (visual evoked potential and electroretinogram), and posterior segment evaluation by ultrasonography. All patients underwent penetrating keratoplasty using donor corneal buttons oversized by 1 mm. Donor corneas were preserved in McCarey-Kaufman medium and used within 24 hours. Donor corneas were punched from the endothelial side using a Teflon block for support. Castroviejo disposable trephines were used to cut the donor and host corneas. While cutting the host cornea, the trephine blade was used to make an approximately 3/4-depth cut after proper centration. The anterior chamber was entered with a ISSN 0161-6420/01/$–see front matter PII S0161-6420(01)00772-2
Vajpayee et al 䡠 Oversized Corneal Grafts Table 1. Graft Outcome at 12 Months (n ⫽ 20) Clear grafts Keratometry (diopters) Anterior chamber depth (mm) Intraocular pressure (mmHg) Astigmatism (diopters) Spherical equivalent (diopters) Visual acuity ⬎ 6/18
17 (85%) 44.10 ⫾ 0.99 2.36 ⫾ 0.42 16.38 ⫾ 2.09 2.38 ⫾ 0.53 ⫺3.23 ⫾ 2.86 14 (70%)
disposable blade, and the cut was completed with curved Vannas scissors. In eyes with an adherent leukoma, a debulking technique with lamellar dissection2 was used initially and then the anterior chamber was entered in an attempt to preserve as much iris tissue as possible. Pupilloplasty, synechiolysis, and anterior segment reconstruction were performed if necessary. Grafts were secured using interrupted 10-0 monofilament nylon sutures. All patients were treated with topical steroids (1% prednisolone acetate), antibiotics (0.3% ciprofloxacin), ocular lubricants, and antiglaucoma medications (0.5% timolol maleate) after surgery. Prednisolone acetate drops were gradually tapered from an initial frequency of 4 hourly in the first week, to 2 times daily up to the sixth month after surgery. All patients were switched over to low-concentration steroids (0.01% dexamethasone) after 6 months. Topical antibiotics and antiglaucoma treatment were discontinued between 2 and 3 weeks after the surgery. No systemic therapy was given except in two cases of high-risk grafts in which systemic prednisolone (1 mg/kg/day) was used. High-risk grafts were defined as grafts with deep vascularization in two or more quadrants and failed grafts because of immunologic rejection. All patients were evaluated at 1 week, 4 weeks, 3 months, 6 months, and 12 months after surgery. Visual acuity, IOP, graft clarity, angle structures, keratometry, and anterior chamber depth were recorded. IOP was measured with the Goldmann applanation tonometer, gonioscopy was done with the Goldmann single-mirror contact lens, and the central anterior chamber depth was measured with A scan ultrasonography. Clear grafts were defined as optically clear corneas with no Descemet’s folds or edema and full visibility of the iris and lens. Graft rejection was diagnosed when there was graft edema without any apparent clinical reason after an initial period of a clear graft for at least 10 days. Loose, vascularized, or infiltrated sutures were removed when necessary. Selective suture removal was done after 6 months to control postkeratoplasty astigmatism if necessary. The final refraction was performed at the 12 month follow-up.
Results Of the 20 patients enrolled in our study, 14 were males and 6 were females, with a mean age of 46.8 ⫾ 17.4 years (range, 15–75 years). The major indications for corneal grafting were corneoiridic scar caused by infectious keratitis in 15 eyes (75%) and failed grafts in 5 eyes (25%). The donor trephination graft size was 8.5 mm in 16 eyes (80%) and 9.0 mm in 4 eyes (20%). Pupilloplasty and anterior segment reconstruction were required in 12 eyes, and goniosynechiolysis was performed in all of the eyes. Mean preoperative IOP recorded was 17.07 ⫾ 2.77 mmHg. IOP was normal throughout the study. The mean IOPs recorded at the fourth week, third month, sixth month and 1 year were 17.78 ⫾ 1.70, 16.94 ⫾ 1.70, 16.73 ⫾ 2.23, and 16.38 ⫾ 2.09 mmHg, respectively. A clear graft was achieved in 85% of eyes at the final follow-up examination (Table 1). Three grafts failed because of graft rejection despite adequate treatment. The preoperative visual
Table 2. Best-corrected Visual Acuity at 12 Months Visual Acuity
No.
Percentage
6/6–6/9 6/12–6/18 6/24–6/60 ⬍6/60
5 9 3 3
25 45 15 15
acuity was less than finger counting in all cases. Fourteen eyes (70%) achieved a best-corrected visual acuity of 6/18 or better, whereas five eyes had a visual acuity of 6/9 or better (Table 2) at the final follow-up. In the eyes with a clear graft the mean corneal astigmatism was 2.38 ⫾ 0.53 diopters (D), the mean spherical equivalent was ⫺3.23 ⫾ 2.86 D (range, ⫺7 D to ⫹ 4 D) and the average keratometry at the end of 12 months of follow-up was 44.10 ⫾ 0.99 D. The mean anterior chamber depth was 2.36 ⫾ 0.42 mm at the final follow-up examination (Table 1). None of the patients had PAS. The graft– host junction was well apposed, and there was no overriding of the edge of the graft at any time in the postoperative period. Four (20%) patients had an attack of graft rejection. Graft rejection was successfully reversed in one patient, but despite intensive therapy the rejection could not be reversed in three patients. All of these patients had been seen by us 4 to 6 days after symptoms had started. Repeat surgery was planned in these three eyes.
Discussion A corneal button oversized by 0.5 mm is traditionally used for corneal grafting in adults.3–5 Corneal opacification along with iridocorneal adhesions is one of the major indications for corneal grafting in this part of the world, and most of these cases have a shallow anterior chamber preoperatively.1,2 It has been our experience that despite optimal suturing and synechiolysis, many patients with preexisting iridocorneal adhesions have a shallow anterior chamber, PAS, and raised IOP during the postoperative period, which often leads to graft failure. It is hypothesized that the lens–iris diaphragm is located more anteriorly in patients with preoperative iridocorneal adhesions and a shallow anterior chamber.6 In these patients, the floppy iris tissue tends to develop a memory for this abnormal position, and thus synechiae frequently form in the postoperative period.6 Moreover, it is a well-documented fact that corneal buttons cut from the endothelial side are smaller than those cut from the epithelial side.7 Although many surgeons prefer to use 0.5-mm oversized grafts, the problems of shallow anterior chamber and occurrence of PAS may still not be eliminated in many of the patients, especially those with extensive iridocorneal adhesions. We had found that grafts oversized by 1 mm provide an adequate anterior chamber depth and increase the morphologic success of corneal grafting in pediatric eyes.6 Therefore we decided to extrapolate this concept to adults with corneal opacities having iridocorneal adhesions, shallow anterior chamber, and PAS. In this study, 1-mm oversized corneal grafts provided an excellent postoperative anterior chamber depth, and none of our patients had PAS. Weiss and Waring8 have advocated a novel technique for
2027
Ophthalmology Volume 108, Number 11, November 2001 objective evaluation of goniosynechiae during anterior segment reconstruction. They use a dental mirror for assessing the PAS intraoperatively after removing the host corneal button. The synechiolysis is done with an iris sweep/cyclodialysis spatula under direct visualization of the angle by looking into the mirror so that a complete synechial release can be objectively ensured. Waring9 also used the dental mirror along with indentation of the limbus with a muscle hook for better visualization of the goniosynechiae and advocated the use of cellulose sponges, smooth forceps, iris sweep, knife, and scissors for releasing various types of synechiae. Using the aforementioned technique with grafts oversized by 0.25 mm to 0.5 mm in eyes with aphakic/ pseudophakic bullous keratopathy, the authors reported PAS in 10% of the cases at the end of the surgery and in 30% of their cases at a follow-up of 6 to 12 months.10 In comparison, in this study using the grafts oversized by 1 mm, none of the cases were detected to have PAS in the postoperative follow-up period. Postkeratoplasty glaucoma is a common occurrence, with several studies citing an incidence ranging from 18% to 75%.1,3,11 This variation may be in part due to differences in surgical techniques, suture tightness, and the definition of glaucoma. Zimmerman et al12 postulated that interruption of Descemet’s membrane by the incision results in loss of anterior support of the trabecular meshwork and decreased outflow facility, leading to glaucoma. A decrease in outflow facility can be prevented by oversized grafts.13,14 Furthermore, several clinical studies have demonstrated a reduction of early postkeratoplasty IOP rise in oversized versus samesized grafts.3,14 However, all the previous studies used 0.25-mm to 0.5-mm oversized grafts when the incidence of postoperative glaucoma was still significant,3,5 and we had observed a similar trend in our clinical practice. In this study we used 1-mm oversized corneal grafts, and none of our patients recorded raised IOP after surgery. The IOP was controlled and stable throughout the study. In our study, 85% eyes (n ⫽ 17) achieved a clear graft, and 70% (n ⫽ 14) had a best-corrected vision of 6/18 or better at 12 months. The mean spherical equivalent in eyes with successful grafts was ⫺3.23 ⫾ 2.86 D. The myopic shift was caused because of the steepening of the corneal curvature subsequent to the use of oversized grafts. Although our study did not have a control group for comparative evaluation, it was apparent that 1-mm oversized corneal grafts provided good anterior chamber depth and had a lower incidence of both PAS and postoperative glaucoma. Most of our patients maintained excellent graft
2028
clarity, had optimal best-corrected visual acuity, and had good anatomic results after surgery. We therefore recommend the use of grafts oversized by 1 mm in eyes with corneal opacification associated with extensive PAS.
References 1. Vajpayee RB, Taherian K, Honavar SG, Negi A. Anterior synechiolysis after keratoplasty. Ophthalmic Surg 1995;26: 264 – 6. 2. Vajpayee RB, Angra SK, Honavar SG, Taherian K. Protection of the iris by lamellar dissection of corneal layers. A technique in penetrating keratoplasty. Cornea 1994;13:16 –9. 3. Zimmerman T, Oslon R, Waltman S, Kaufman H. Transplant size and elevated intraocular pressure: postkeratoplasty. Arch Ophthalmol 1978;96:2231–3. 4. Foulks GN, Perry HD, Dohlman CH. Oversize corneal donor grafts in penetrating keratoplasty. Ophthalmology 1979;86: 490 – 4. 5. Oslon RJ, Mattingly TP, Waltman SR, Kaufman HE. Refractive variation and donor tissue size in aphakic keratoplasty: a prospective randomized study. Arch Ophthalmol 1979;97: 1480 –1. 6. Vajpayee RB, Ramu M, Panda A, et al. Oversized grafts in children. Ophthalmology 1999;106:829 –32. 7. Olson RJ. Variation in corneal graft size related to trephine technique. Arch Ophthalmol 1979;97:1323–5. 8. Weiss JS, Waring GO III. Dental mirror for goniosynechiolysis during penetrating keratoplasty. Am J Ophthalmol 1985; 100:331–2. 9. Waring GO III. Management of pseudophakic corneal edema with reconstruction of the anterior ocular segment. Arch Ophthalmol 1987;105:709 –15. 10. Waring GO III, Kenyon KR, Gemmill MC. Results of anterior segment reconstruction for aphakic and pseudophakic corneal edema. Ophthalmology 1988;95:836 – 41. 11. Oslon RJ, Kaufman HE. Prognostic factors of intraocular pressure after aphakic keratoplasty. Am J Ophthalmol 1978; 86:510 –5. 12. Zimmerman TJ, Krupin T, Grodzki W, Waltman SR. The effect of suture depth on outflow facility in penetrating keratoplasty. Arch Ophthalmol 1978;96:505– 6. 13. Oslon RJ, Kaufman HE. A mathematical description of causative factors and prevention of elevated intraocular pressure after keratoplasty. Invest Ophthalmol Vis Sci 1977;16:1085– 92. 14. Oslon RJ. Aphakic keratoplasty: determining donor tissue size to avoid elevated intraocular pressure. Arch Ophthalmol 1978; 96:2274 – 6.