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Pellucid marginal corneal degeneration: Report on corrective surgery
Pellucid marginal corneal degeneration: Report on corrective surgery Seymour Dubroff, M.D.
\8 TR'\C 'liC "flll corn 'al \\ 'dg' I" 'ction \\u P'I'form ,d to corT' ,t th \ i lIal impairment in th ' I 'ft '\ of u :30-\ 'ar-old mal, "ho 1I 'I' ,d from hilut'~al p 'l1l1 'i~1 marginal d'~ 'n 'mtion. Th' (>atient had \ i lIal impaiJ'1ll 'nt in hoth .~ .,~ it \HI' "or ... ' in th ' I·ft. B "t COlT 'ct ·ct ,i lIal aCllit~in th 'left " ' h·fol'· urg'I') \\<,,2 \,ith l:-.:-diopt r (D )of 'ol'n 'ul a'ti~lllati m. Ht '1' uJ'~ ·r). ·orrect·
(: )rll 'al protrtl 1111 • k('I.ltO ·OIllIS. k 'I" .Itogloh..... P 1111 , 'id mart!illal <:01"11(',11
cases, instruments and notes
dt't!('IIt'1 atlOl . strollial thillllillt!. \\ 'd~' r' ,tt iOIl
--------------~
------------------~
Much has been written about keratoconus and related corneal thinning disorders .1. 2 .3 Little new information , however, has become available about pellucid marginal corneal degeneration, a disorder characterized by thinning of the inferior peripheral portion of the cornea bilaterally, without clouding, scarring, or vascularization. More importantly, little has been available about surgical procedures to improve visual acuity in severe cases, This paper reports the results of a successful wedge resection procedure for pellucid degeneration.
Presented ill part at th e Symposium on Cataract, IOL alld Rejractive Surgery, Orlando , Florida, April 1987, and at th e Kerato-Rejractit)e Society Meeting , Nelc Or/cans, Louisia/la , Not'ember 1986. Reprint requests to SeYlIlour Dubroff M.D. , Dubroff Eye Surgery Cente!: 890.5 Fairvietc Road , Silver Spring . Maryland 20910.
J CATARACT REFRACT
SURG -VOL 15, JANUARY 1989
89
CASE REPORT In 1985, a 30-vear-old white Middle Eastern male presented with p~ogressive visual deterioration of both eyes. Best corrected visual acuity with spectacles was 20/50 in the right eye and 20/800 in the left eye. No further improvement was possible with a spectacle lens, contact lens or a combination. The refraction was +0.50 X -2 ..50 X 90 in the right eye and -1.75 X - 8.00 X 90 in the left eye. Keratometry was 42 X 90148 X 180 in the right eye and .'37 X 90/52 ..5 X 180 in the left eye. The mires were irregular. The corneas had arcuate thinning inferiorly just within the limbus from the 4 o'clock to 8 o'clock positions. The band of thinning in the left eye was
Fig. 1.
(Dubroff) A schematic representation ()f the surgical plan illustrating how a properl~' selected wedge resecti()n can restore normal corneal topography.
Fig. 2.
(Dubroff) Transilluminated cornea dem()nstrating the inferior protrusion of the c()rnea just ahoye the l()wer lid margin.
90
approximately 1..5 mm in width, \vas clear, and was thinner than that in the right eye. There was no vascularization, scarring, or lipid f()J'mation. The corneas protruded inferiorly above the thinned area. The intraocular pressure measured 15 mm Hg in the right eye and 16 mm Hg in the left eye. Fundus examination was normal in both eyes. Macular function studies and visual fields were also normal. The clinical diagnosis based on these findings was pellucid marginal degeneration in both eyes. After being informed that wedge resection had never been used for this procedure, the patient consented to the operation on his left eye. The exact amount of cornea to be resected could not be determined bef()l'e surgery, but it was estimated that the patient had approximately 1..5 mm lengthening of the cornea in the vertical meridian, and this \vas the wedge resection size. The general principles of the surgical procedure consist of removing a wedge of the aHected corneal tissue and reapposing the cornea to restore normal contour (Figure 1). A preoperative photograph of the eye in left gaze demonstrates the inferior protrusion of the cornea (Figure 2). vVe were able to transilluminate
Fig. 3.
(Dubrofl) Outline ()f the wedge of corneal tisslle to he rE'sected. F()r sllch a SE'\'erp case the center ()f the wedge is 1..'5mm.
J CATARACT REFRACT Sl'RG- VOL 1.3, JAl\lTARY 1989
Fig. 5.
Fig. 4.
(Duhroffi Resecting the wedge with corneal scissors. It is important to overlay the cut edges to restore normal corneal thickness.
the cornea to demonstrate the derangement of the contour. Anesthesia was 0.7.5% bupivacaine: :3 cc were injected into the retrobulbar space and .3 cc over the zygoma for lid akinesia. Bridle sutures were placed beneath the inferior and the superior rectus muscles. An inferior crescentic corneal wedge was outlined from the 4 o'clock to the 8 o'clock position. The outer more peripheral incision \vas at the limbus. A 1.0 mm paracentesis incision \vas made at the 3 o'clock corneal position and the chamber was filled with sodium hyaluronate (Healon®) (Figure :3). Before excision of the corneal tissue, the inferior bulbar conjunctiva was undermined and retracted from the limbus. Light cautery was applied for hemostasis (Figure 4). The outlined wedge of corneal tissue was resected with corneal scissors. The corneal incisions were made obliquely so the reapposed cornea would be reinforced and thickened. The gap created by the resection was closed, using interrupted 10-0 nylon sutures (Figure .5). The suture knots were rotated to avoid irritation. Ointment and a dressing were then applied.
RESULTS Histopathologic examination of the resected tissue revealed thinning of Bowman's membrane and of the
(Duhroffi The corneal edges have he en sutured using interrupted 10-0 nylon sutures.
stromal layer but no inflammatory or other pathological features. Immediately after the surgery, the patient was overcorrected by 12 diopters (D) and the keratometry reading was 39 X ISO/51 X 90. At three months, the corneal curvature stabilized with 5 D of against-therule astigmatism. The keratometry reading was 41 X 80/46 X 170. The visual acuitv was 20/S0 without correction and 20/50 + with a spectacle correction of + 1.50 = + 3.00 X 150; before surgery, correction by any means was impossible (Figure 6). The patient was satisfied with the result and requested surgery on the fellow eye, which I declined since the degree of the visual handicap did not warrant it. But because of the patient's visual requirements as a noncommissioned officer, I further reduced the astig-
Fig. 6.
(Dubroff) The cornea postoperatively. illuminated by transillumination. revealing now a normal corneal topography.
J CATARACT REFRACT StTRG-\'OL 1.5. JANlTARY 191>9
91
matism in the left eye with relaxing incisions just inside the limbus at 3 o'clock and 9 o'clock. The final astigmatic spectacle correction was 3 D .The keratometry reading was 39/44 x 137. Postoperatively the patient's best corrected visual acuity was 20/50 + with + 1.50 x + 3.00 x 150 (Figure 7). DISCUSSION Pellucid marginal corneal degeneration is characterized by bilateral, clear, inferior, peripheral corneal thinning. Typically the cornea remains clear, yet in certain cases vascularization and scarring occur. 1 A The term "pellucid" was introduced by Schlaeppi to describe bilateral inferior thinning of the peripheral cornea ..5 The thinning area is usually 1 mm to 2 mm in width and extends from 4 o'clock to 8 o'clock, with the greatest thinning occurring within the limbus. This results in a misshapen cornea. In keratoconus, the most frequently observed corneal shape disorder, 2. the center of the cornea assumes a conical configuration because of protrusion and thinning; that is, the center thins and bows forward and the cornea protrudes anteriorly. Instead of being round, the corneal center assumes a conical shape in advanced keratoconus. In keratoglobus, a less common variant of
Fig. 7.
92
(Dubroffi A modified f()rm of radial keratotom,' was performed to reduee the against-the-rule astign;atism from .5 D to 3 D.
J CATARACT
the disorder, the entire cornea usuallv thins and protrudes. In pellucid corneal degenerati~n, however, the thinning occurs in an inferior arc and the corneal protrusion takes place above the thinned area. Progressive thinning inevitably results in irregular and high astigmatism, almost always precluding contact lens or spectacle correction in severe cases. In the patient reported, no refractive correction before surgery was possible. Clinicopathological study of pellucid marginal degeneration by Rodrigues et al. 6 using collagenase assay and electron microscopy suggests that the disorder is a variant of keratoconus. A study of20 Japanese patients with pellucid degeneration and 1,625 patients with keratoconus has revealed that 17 patients with pellucid degeneration also were afflicted with keratoconus in the central portion of the cornea.' In my patient there was no evidence of keratoconus. Both sexes are equally vulnerable to pellucid degeneration. Thus far, no evidence of hereditarv transmission has been detected, nor has the ca~lse of the disorder been known. Neither the patient's parents nor his sihlings suffered from the disorder and the patient himself had no previous eye problems. His general health was excellent. The corneal degeneration in pellucid marginal degeneration is usually first detected behveen 20 and 40 years of age. Although affliction among whites is extremely rare ,' the patient in this report was a white Middle Eastern male. In 1981, I observed pellucid degeneration in a German white male in his 70s. Because of his age and tolerance of the condition, he and I decided to forego a surgical correction. However, the procedure that occurred to me at the time was an inferior wedge resection with overlapping of thin corneal section on repair. Troutman H popularized the use of wedge resection for treatment of high degrees of corneal astigmatism, and in 1984 Caldwell et alY reported the use of a similar procedure in their treatment of Terrien's marginal degeneration. References in the literature to previous cases of surgical correction of pellucid marginal degeneration are few in number and usually deal with lamellar keratoplasty, diathermy and thermokeratoplasty, and o"ersized corneal grafts.l ·1O - 14 Review of these reports leaves one uncertain about visual outcome in severe cases. Penetrating keratoplasty has been used but is not an entirelv satisfactorv method of visual corrective surgery in pellucid degen~ration. As Krachmer, Feder, and Belin) point out, penetrating keratoplasty as surgical correction presents a number of problems because "larger than normal grafts are needed to provide a clear central visual axis. Corneal grafts of 9.0 111m or larger are required. In addition, the proximity of grafts to the inferior limbus makes graft vascularization and early suture erosion more com-
REFRACT SllRG-YOL 1.5, JA/liUARY 1989
mon." Furthermore, the graft is always eccentrically placed. The wedge resection procedure proved successful in greatly improving the patient's severely impaired vision. Since the surgery, the patient has maintained good visual acuity and comfort with no evidence of additional corneal degeneration. As far as I know, no such procedure has been reported for surgical correction of pellucid marginal degeneration. The procedure, therefore, may be an effective corrective surgery for this unique disorder. More cases using this surgical approach are required before a definitive conclusion about its effectiveness can be drawn. REFERENCES 1. Krachmer JH, Feder RS, Belin MW: Keratoconus and related
2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
noninflammatory corneal thinning disorders. Surv Ophthalmol 28:293-322, 1984 Insler MS, Baumann JD: Corneal thinning syndromes. Ann Ophthalmol 18:74-75, 1986 Hallermann W: liber atypischen Keratokonus und andere konstitutionell-progressive Hornhautektasien . Klin Monatsbl Augenheilkd 156: 161-173, 1970 Krachmer JH: Pellucid marginal corneal degeneration. Arch Ophthalmol96:1217-1221, 1978 . Schlaeppi V: La dystophie marginale inferieure pellucide de la cornee. Mod Prabl Ophthalmol 1:672-677, 1957 Rodrigues MM, Newsome DA, Krachmer JH, Eiferman RA: Pellucid marginal corneal degeneration: A clinicopathologic study of two cases. Exp Eye Res 33:277-288, 1981 Kayazawa F, Nishimura K, Kodama Y, Tsuji T, et al: Keratoconus with pellucid marginal corneal degeneration. Arch Ophthalmol 102:895-896, 1984 Troutman RC : Corneal wedge resections and relaxing incisions for postkeratoplasty astigmatism. lnt Ophthalmol Clin 23(4):161-168, 1983 Caldwell DR, Insler MS , Boutros G , Hawk T: Primary surgical repair of severe peripheral marginal ectasia in Terrien's marginal degeneration . Am ] Ophthalmol 97:332-336 , 1984 Schanz lin DJ, Sarno EM, Robin JB : Crescentic lamellar keratoplasty for pellucid marginal degeneration (letter). Am ] Ophthalmol 96:253-254, 1983 Zucchini G: Su di un caso di degenerazione margin ale della cornea-varieta inferiore pellucida - studio c1inico ed istologico . Ann Ottalmol Clin Oculist 88:47-56, 1962 Francois J, Hanssens M, Stockmans L: Degenerescence marginale pellucide de la cornee. Ophthalmologica 155:337-356, 1968. Schnitzer JI : Crescentic lamellar keratoplasty for pellucid marginal degeneration (letter). Am] Ophthalmol 97:250-251, 1984 Schanzlin DJ, Sarno EM , Robin JB: Reply. Am] Ophthalmol 97:251-252, 1984
Modified pocket incision: A simplified technique for astigmatism control and wound closure Peter C. Kansas, M.D.
ABSTRACT
Advantages of small incision cataract surgery are widely known whether performed with phacoemuIsifieation or lIWlual fragmentation {phaoofracture}. A modified pocket incision technique that allows predictable astigmatism control without. reliance on eX-pe:nsive intraoperative lreratometers is desc~.This techmque requires lessdissectio~ . than the pocket incision and is less likely to bleed. Key.Words: astigmatism, modified pockeUncisWn'~ phacoemulsification . ..
The past several years have revealed a great interest within the ophthalmic surgical community in minimizing astigmatism. Various techniques have been espoused and instrumentation developed in the form of intraoperative keratometers to assist the surgeon. Small incision surgery has contributed significantly to reducing postsurgical astigmatism, which in turn has been possible by phacoemulsification. More recently, it has been demonstrated that manual nuclear fragmentation is also possible through a small incision. The pocket incision has been shown to enhance the control of surgically induced astigmatism . This, however, requires more dissection in a relatively vascular bed and requires the surgeon to work through a relatively long microtunnel to reach the anterior chamber. The modified pocket incision represents a simplified version of the pocket incision that decreases the amount of scleral dissection and the length of the scleral tunnel. It retains the advantage of astigmatism control and all other advantages of a small incision; namely, a more stable wound, a faster healing wound, and more rapid vision stabilization. Reprint requests to Peter C. Kansas, M.D., Capital District Eye Surgery Associates, 747 Madison Avenue, Albany, New York 12208.
J CATARACT REFRACT SURe-VOL 15, JANUARY 1989
93
\8 TR'\C 'liC "flll corn 'al \\ 'dg' I" 'ction \\u P'I'form ,d to corT' ,t th \ i lIal impairment in th ' I 'ft '\ of u :30-\ 'ar-old mal, "ho 1I 'I' ,d from hilut'~al p 'l1l1 'i~1 marginal d'~ 'n 'mtion. Th' (>atient had \ i lIal impaiJ'1ll 'nt in hoth .~ .,~ it \HI' "or ... ' in th ' I·ft. B "t COlT 'ct ·ct ,i lIal aCllit~in th 'left " ' h·fol'· urg'I') \\<,,2 \,ith l:-.:-diopt r (D )of 'ol'n 'ul a'ti~lllati m. Ht '1' uJ'~ ·r). ·orrect·
(: )rll 'al protrtl 1111 • k('I.ltO ·OIllIS. k 'I" .Itogloh..... P 1111 , 'id mart!illal <:01"11(',11
cases, instruments and notes
dt't!('IIt'1 atlOl . strollial thillllillt!. \\ 'd~' r' ,tt iOIl
--------------~
------------------~
Much has been written about keratoconus and related corneal thinning disorders .1. 2 .3 Little new information , however, has become available about pellucid marginal corneal degeneration, a disorder characterized by thinning of the inferior peripheral portion of the cornea bilaterally, without clouding, scarring, or vascularization. More importantly, little has been available about surgical procedures to improve visual acuity in severe cases, This paper reports the results of a successful wedge resection procedure for pellucid degeneration.
Presented ill part at th e Symposium on Cataract, IOL alld Rejractive Surgery, Orlando , Florida, April 1987, and at th e Kerato-Rejractit)e Society Meeting , Nelc Or/cans, Louisia/la , Not'ember 1986. Reprint requests to SeYlIlour Dubroff M.D. , Dubroff Eye Surgery Cente!: 890.5 Fairvietc Road , Silver Spring . Maryland 20910.
J CATARACT REFRACT
SURG -VOL 15, JANUARY 1989
89
CASE REPORT In 1985, a 30-vear-old white Middle Eastern male presented with p~ogressive visual deterioration of both eyes. Best corrected visual acuity with spectacles was 20/50 in the right eye and 20/800 in the left eye. No further improvement was possible with a spectacle lens, contact lens or a combination. The refraction was +0.50 X -2 ..50 X 90 in the right eye and -1.75 X - 8.00 X 90 in the left eye. Keratometry was 42 X 90148 X 180 in the right eye and .'37 X 90/52 ..5 X 180 in the left eye. The mires were irregular. The corneas had arcuate thinning inferiorly just within the limbus from the 4 o'clock to 8 o'clock positions. The band of thinning in the left eye was
Fig. 1.
(Dubroff) A schematic representation ()f the surgical plan illustrating how a properl~' selected wedge resecti()n can restore normal corneal topography.
Fig. 2.
(Dubroff) Transilluminated cornea dem()nstrating the inferior protrusion of the c()rnea just ahoye the l()wer lid margin.
90
approximately 1..5 mm in width, \vas clear, and was thinner than that in the right eye. There was no vascularization, scarring, or lipid f()J'mation. The corneas protruded inferiorly above the thinned area. The intraocular pressure measured 15 mm Hg in the right eye and 16 mm Hg in the left eye. Fundus examination was normal in both eyes. Macular function studies and visual fields were also normal. The clinical diagnosis based on these findings was pellucid marginal degeneration in both eyes. After being informed that wedge resection had never been used for this procedure, the patient consented to the operation on his left eye. The exact amount of cornea to be resected could not be determined bef()l'e surgery, but it was estimated that the patient had approximately 1..5 mm lengthening of the cornea in the vertical meridian, and this \vas the wedge resection size. The general principles of the surgical procedure consist of removing a wedge of the aHected corneal tissue and reapposing the cornea to restore normal contour (Figure 1). A preoperative photograph of the eye in left gaze demonstrates the inferior protrusion of the cornea (Figure 2). vVe were able to transilluminate
Fig. 3.
(Dubrofl) Outline ()f the wedge of corneal tisslle to he rE'sected. F()r sllch a SE'\'erp case the center ()f the wedge is 1..'5mm.
J CATARACT REFRACT Sl'RG- VOL 1.3, JAl\lTARY 1989
Fig. 5.
Fig. 4.
(Duhroffi Resecting the wedge with corneal scissors. It is important to overlay the cut edges to restore normal corneal thickness.
the cornea to demonstrate the derangement of the contour. Anesthesia was 0.7.5% bupivacaine: :3 cc were injected into the retrobulbar space and .3 cc over the zygoma for lid akinesia. Bridle sutures were placed beneath the inferior and the superior rectus muscles. An inferior crescentic corneal wedge was outlined from the 4 o'clock to the 8 o'clock position. The outer more peripheral incision \vas at the limbus. A 1.0 mm paracentesis incision \vas made at the 3 o'clock corneal position and the chamber was filled with sodium hyaluronate (Healon®) (Figure :3). Before excision of the corneal tissue, the inferior bulbar conjunctiva was undermined and retracted from the limbus. Light cautery was applied for hemostasis (Figure 4). The outlined wedge of corneal tissue was resected with corneal scissors. The corneal incisions were made obliquely so the reapposed cornea would be reinforced and thickened. The gap created by the resection was closed, using interrupted 10-0 nylon sutures (Figure .5). The suture knots were rotated to avoid irritation. Ointment and a dressing were then applied.
RESULTS Histopathologic examination of the resected tissue revealed thinning of Bowman's membrane and of the
(Duhroffi The corneal edges have he en sutured using interrupted 10-0 nylon sutures.
stromal layer but no inflammatory or other pathological features. Immediately after the surgery, the patient was overcorrected by 12 diopters (D) and the keratometry reading was 39 X ISO/51 X 90. At three months, the corneal curvature stabilized with 5 D of against-therule astigmatism. The keratometry reading was 41 X 80/46 X 170. The visual acuitv was 20/S0 without correction and 20/50 + with a spectacle correction of + 1.50 = + 3.00 X 150; before surgery, correction by any means was impossible (Figure 6). The patient was satisfied with the result and requested surgery on the fellow eye, which I declined since the degree of the visual handicap did not warrant it. But because of the patient's visual requirements as a noncommissioned officer, I further reduced the astig-
Fig. 6.
(Dubroff) The cornea postoperatively. illuminated by transillumination. revealing now a normal corneal topography.
J CATARACT REFRACT StTRG-\'OL 1.5. JANlTARY 191>9
91
matism in the left eye with relaxing incisions just inside the limbus at 3 o'clock and 9 o'clock. The final astigmatic spectacle correction was 3 D .The keratometry reading was 39/44 x 137. Postoperatively the patient's best corrected visual acuity was 20/50 + with + 1.50 x + 3.00 x 150 (Figure 7). DISCUSSION Pellucid marginal corneal degeneration is characterized by bilateral, clear, inferior, peripheral corneal thinning. Typically the cornea remains clear, yet in certain cases vascularization and scarring occur. 1 A The term "pellucid" was introduced by Schlaeppi to describe bilateral inferior thinning of the peripheral cornea ..5 The thinning area is usually 1 mm to 2 mm in width and extends from 4 o'clock to 8 o'clock, with the greatest thinning occurring within the limbus. This results in a misshapen cornea. In keratoconus, the most frequently observed corneal shape disorder, 2. the center of the cornea assumes a conical configuration because of protrusion and thinning; that is, the center thins and bows forward and the cornea protrudes anteriorly. Instead of being round, the corneal center assumes a conical shape in advanced keratoconus. In keratoglobus, a less common variant of
Fig. 7.
92
(Dubroffi A modified f()rm of radial keratotom,' was performed to reduee the against-the-rule astign;atism from .5 D to 3 D.
J CATARACT
the disorder, the entire cornea usuallv thins and protrudes. In pellucid corneal degenerati~n, however, the thinning occurs in an inferior arc and the corneal protrusion takes place above the thinned area. Progressive thinning inevitably results in irregular and high astigmatism, almost always precluding contact lens or spectacle correction in severe cases. In the patient reported, no refractive correction before surgery was possible. Clinicopathological study of pellucid marginal degeneration by Rodrigues et al. 6 using collagenase assay and electron microscopy suggests that the disorder is a variant of keratoconus. A study of20 Japanese patients with pellucid degeneration and 1,625 patients with keratoconus has revealed that 17 patients with pellucid degeneration also were afflicted with keratoconus in the central portion of the cornea.' In my patient there was no evidence of keratoconus. Both sexes are equally vulnerable to pellucid degeneration. Thus far, no evidence of hereditarv transmission has been detected, nor has the ca~lse of the disorder been known. Neither the patient's parents nor his sihlings suffered from the disorder and the patient himself had no previous eye problems. His general health was excellent. The corneal degeneration in pellucid marginal degeneration is usually first detected behveen 20 and 40 years of age. Although affliction among whites is extremely rare ,' the patient in this report was a white Middle Eastern male. In 1981, I observed pellucid degeneration in a German white male in his 70s. Because of his age and tolerance of the condition, he and I decided to forego a surgical correction. However, the procedure that occurred to me at the time was an inferior wedge resection with overlapping of thin corneal section on repair. Troutman H popularized the use of wedge resection for treatment of high degrees of corneal astigmatism, and in 1984 Caldwell et alY reported the use of a similar procedure in their treatment of Terrien's marginal degeneration. References in the literature to previous cases of surgical correction of pellucid marginal degeneration are few in number and usually deal with lamellar keratoplasty, diathermy and thermokeratoplasty, and o"ersized corneal grafts.l ·1O - 14 Review of these reports leaves one uncertain about visual outcome in severe cases. Penetrating keratoplasty has been used but is not an entirelv satisfactorv method of visual corrective surgery in pellucid degen~ration. As Krachmer, Feder, and Belin) point out, penetrating keratoplasty as surgical correction presents a number of problems because "larger than normal grafts are needed to provide a clear central visual axis. Corneal grafts of 9.0 111m or larger are required. In addition, the proximity of grafts to the inferior limbus makes graft vascularization and early suture erosion more com-
REFRACT SllRG-YOL 1.5, JA/liUARY 1989
mon." Furthermore, the graft is always eccentrically placed. The wedge resection procedure proved successful in greatly improving the patient's severely impaired vision. Since the surgery, the patient has maintained good visual acuity and comfort with no evidence of additional corneal degeneration. As far as I know, no such procedure has been reported for surgical correction of pellucid marginal degeneration. The procedure, therefore, may be an effective corrective surgery for this unique disorder. More cases using this surgical approach are required before a definitive conclusion about its effectiveness can be drawn. REFERENCES 1. Krachmer JH, Feder RS, Belin MW: Keratoconus and related
2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
noninflammatory corneal thinning disorders. Surv Ophthalmol 28:293-322, 1984 Insler MS, Baumann JD: Corneal thinning syndromes. Ann Ophthalmol 18:74-75, 1986 Hallermann W: liber atypischen Keratokonus und andere konstitutionell-progressive Hornhautektasien . Klin Monatsbl Augenheilkd 156: 161-173, 1970 Krachmer JH: Pellucid marginal corneal degeneration. Arch Ophthalmol96:1217-1221, 1978 . Schlaeppi V: La dystophie marginale inferieure pellucide de la cornee. Mod Prabl Ophthalmol 1:672-677, 1957 Rodrigues MM, Newsome DA, Krachmer JH, Eiferman RA: Pellucid marginal corneal degeneration: A clinicopathologic study of two cases. Exp Eye Res 33:277-288, 1981 Kayazawa F, Nishimura K, Kodama Y, Tsuji T, et al: Keratoconus with pellucid marginal corneal degeneration. Arch Ophthalmol 102:895-896, 1984 Troutman RC : Corneal wedge resections and relaxing incisions for postkeratoplasty astigmatism. lnt Ophthalmol Clin 23(4):161-168, 1983 Caldwell DR, Insler MS , Boutros G , Hawk T: Primary surgical repair of severe peripheral marginal ectasia in Terrien's marginal degeneration . Am ] Ophthalmol 97:332-336 , 1984 Schanz lin DJ, Sarno EM, Robin JB : Crescentic lamellar keratoplasty for pellucid marginal degeneration (letter). Am ] Ophthalmol 96:253-254, 1983 Zucchini G: Su di un caso di degenerazione margin ale della cornea-varieta inferiore pellucida - studio c1inico ed istologico . Ann Ottalmol Clin Oculist 88:47-56, 1962 Francois J, Hanssens M, Stockmans L: Degenerescence marginale pellucide de la cornee. Ophthalmologica 155:337-356, 1968. Schnitzer JI : Crescentic lamellar keratoplasty for pellucid marginal degeneration (letter). Am] Ophthalmol 97:250-251, 1984 Schanzlin DJ, Sarno EM , Robin JB: Reply. Am] Ophthalmol 97:251-252, 1984
Modified pocket incision: A simplified technique for astigmatism control and wound closure Peter C. Kansas, M.D.
ABSTRACT
Advantages of small incision cataract surgery are widely known whether performed with phacoemuIsifieation or lIWlual fragmentation {phaoofracture}. A modified pocket incision technique that allows predictable astigmatism control without. reliance on eX-pe:nsive intraoperative lreratometers is desc~.This techmque requires lessdissectio~ . than the pocket incision and is less likely to bleed. Key.Words: astigmatism, modified pockeUncisWn'~ phacoemulsification . ..
The past several years have revealed a great interest within the ophthalmic surgical community in minimizing astigmatism. Various techniques have been espoused and instrumentation developed in the form of intraoperative keratometers to assist the surgeon. Small incision surgery has contributed significantly to reducing postsurgical astigmatism, which in turn has been possible by phacoemulsification. More recently, it has been demonstrated that manual nuclear fragmentation is also possible through a small incision. The pocket incision has been shown to enhance the control of surgically induced astigmatism . This, however, requires more dissection in a relatively vascular bed and requires the surgeon to work through a relatively long microtunnel to reach the anterior chamber. The modified pocket incision represents a simplified version of the pocket incision that decreases the amount of scleral dissection and the length of the scleral tunnel. It retains the advantage of astigmatism control and all other advantages of a small incision; namely, a more stable wound, a faster healing wound, and more rapid vision stabilization. Reprint requests to Peter C. Kansas, M.D., Capital District Eye Surgery Associates, 747 Madison Avenue, Albany, New York 12208.
J CATARACT REFRACT SURe-VOL 15, JANUARY 1989
93