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ORIGINAL ARTICLE
Year : 1983  |  Volume : 31  |  Issue : 4  |  Page : 369-374

Persistent elevation of intraocular pressure following keratoplasty


Department of Ophthalmology University of Maryland School of Medicine Baltimore, Maryland, USA

Correspondence Address:
Verinder S Nirankari
M.D. Cornea Service University Hospital 22 S. Greene Street Baltimore, Md. 21201
USA
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Source of Support: None, Conflict of Interest: None


PMID: 6376342

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How to cite this article:
Karesh JW, Nirankari VS. Persistent elevation of intraocular pressure following keratoplasty. Indian J Ophthalmol 1983;31:369-74

How to cite this URL:
Karesh JW, Nirankari VS. Persistent elevation of intraocular pressure following keratoplasty. Indian J Ophthalmol [serial online] 1983 [cited 2020 Apr 7];31:369-74. Available from: http://www.ijo.in/text.asp?1983/31/4/369/27557



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The association between penetrating keratoplasty and the development of posto­perative increases in intraocular pressure has been vigorously discussed since it was first noted by Irvine and Kaufman in 1969[1]. A variety of factors have been studied to try to better understand the mechanisms involved in the elevation of intraocular pressure following keratoplasty. Graft size[2],[3],[4],[5],[6], suture technique[3],[4],[7] and iridocorneal compression[4],[7] have all been felt to have some effect on postoperative intraocular pressure increase. Other factors, most especially aphakia,[2],[8] have also been studied. However, most studies have been concerned with early elevation in intraocular pressure rather than long term elevation of pressures following keratoplasty (> 3 months). A retrospective study of 80 consecutive penetrating keratop­lasties performed over a two year period at our institution was undertaken in order to determine the factors involved in long term elevation of intraocular pressure following this procedure.


  Material and methods Top


80 consecutive penetrating keratoplasties with a minimum follow-up of 12 months (average 30 months) were retrospectively analyzed to determine the factors related to postoperative glaucoma (IOP > 21 mm Hg). All procedures were performed by one surgeon (VSN) between September 1979 and October 1981. Preoperative diagnoses are listed in [Table - 1] and include aphakic and pseudophakic bullous keratopathies, Fuch's dystrophy, keratoconus, trauma, corneal scarring related to a variety of causes, and corneal dystrophy. There were 4 reoperations [Table - 1]. Preoperatively, 63 eyes had no glaucoma, while 17 eyes had glaucoma. All eyes with glaucoma had their pressures controlled (lOP < 21 mm Hg) with topical and/or oral medications prior to undergoing surgery, including Pilocarpine 4%, Timolol 0.5% an epinephrine compound and carbonic anhydrase inhibitors.

All penetrating keratoplasties were performed in a standard manner. Flieringa rings were used in all cases. After donor button size was determined, the host cornea was superficially marked with the appropriate trephine. Usually 7.5 mm host bed size was selected except in patients with keratoconus where a 8mm host size was used. Attention was then directed towards the donor cornea which had previously been stored in M-K media. The donor cornea was placed endo­thelial side up on a teflon block and the donor button excised. A trephine was then used to groove the previously marked host cornea to one half its thickness. The anterior chamber was entered through the groove using a Ziegler blade and the corneal scissors. If the eye was aphakic and an anterior vitrectomy needed, a Peyman vitrector was used until all vitreous was removed from the anterior chamber and angle and the vitreous had fallen back behind the pupil. When present, synechiae and membranes were removed using blunt dissection and cutting. When lens removal was also performed a peripheral iridectomy was made. In cases of intracapsular extrac­tion 1 :7500 Alpha Chymotrypsin was instilled prior to cryoextraction. In cases of extracapsular extraction, following anterior capsulotomy, the nucleus was expressed and cortical material irrigated and aspirated using balanced salt solution and a syringe fitted with a 25 gauge irrigation tip. When interrupted sutures were used, 16 10-0 nylon or proline sutures were placed in equally spaced bites around the cornea. When running sutures were used eight interrupted cardinal sutures of 9-0 silk were placed followed by a 10-0 continuous nylon or proline suture in 16 equal bites around the cornea. Following this, the cardinal sutures were removed. The anterior chamber was reformed as necessary with balanced salt solution.

Postoperatively patients were routinely treated with topical corticosteroids. Intrao­cular pressure was measured by pneumoto­nometry daily for five days, weekly for a month, and at all subsequent routine posto­perative visits. Therapy for increased intraocular pressure was instituted when pressures were measured at > 25mm Hg in the immediate postoperative period. (> three months) and > 21mm in the late postopera­tive period(>three months). If the intraocular pressure could not be controlled medically, cyclocryotherapy andjor a filtration procedure was performed.

All the data was analysed using Pearson's chi squared statistic with Yates' correction and the Students t-test.


  Observations Top


Incidence of Glaucoma

80 eyes are included in this study. Preoperatively only 17 eyes (21%) had elevated intraocular pressures (Group I). Of these 17 eyes, 14 (82%) continued to have elevated pressures in both the early (< three months) and late postoperative period (> than three months). One eye developed pressure elevation only in the late period. There were 63 eyes without preoperative glaucoma (Group II). Eleven (17%) developed early postoperative increases in pressure. However, only 8 (13%) continued to have pressure elevation on long term followup. Steriod responsiveness was a factor in three of these eight while the remaining 5 under­went combined procedures of cataract extraction and keratoplasty. The difference in the incidence of elevated intraocular pressure following surgery between the two groups was statistically significant (P < .001)

Combined Procedures. Pseudophakia, Reopera­tions

There were 25 combined procedures 21 eyes had intracapsular extractions and 4 eyes had extractions with keratoplasty. Five of these had preoperative glaucoma that continued postoperatively. Four nonglauco­matous eyes developed early pressure eleva­tions and in three of these, the pressure elevations continued into the late postopera­tive period, for a total of eight eyes with persistent glaucoma.

Seven eyes had pseudophakic bullous keratopathy. In two of these, the intraocular lens were removed during keratoplasty and four eyes underwent a vitrectomy. Once eye had glaucoma both before and after surgery while one eye developed it only in the late postoperative period.

There were four reoperations. One eye had two reoperations each of which ended in rejection of the donor corneal button and the development of synechiae, a retrocorneal membrane and severe glaucoma which requi­red cyclocryotherapy.

There were an additional two eyes who underwent reoperations. One had kerato conjunctivitis sicca and had dehiscence of his graft following blunt trauma. He did not show pressure after his surgery. The other patient underwent a reoperation following primary graft failure. She had glaucoma both preoperatively and postoperatively.

Analysis of these eyes failed to reveal any statistically significant increase in the inci­dence of glaucoma in either the combined procedures, the pseudophakic eyes, and the eyes who underwent reoperations.

Phakia versus Aphakia

There were 27 phakic and 53 aphakic keratoplasties. In the phakic group, two eyes had glaucoma preopera tively. These eyes continued to have glaucoma postoperatively. Only one of the 25 phakic eyes without glaucoma preoperatively developed it posto­peratively. This patient was a steroid responder. There were a total of 3 eyes with long term pressure elevations in this group.

In the aphakic group 15 eyes (28%) had glaucoma prior to surgery. Thirteen of these continued to have glaucoma following surgery. Ten eyes without preoperative glaucoma developed it in the early period. Five of these eyes showed resolution of their glaucoma. An additional eye developed glaucoma only in the late period for a total number of 7 eyes that did not have glaucoma preoperative but showed persistent elevations of intraocular pressure following aphakic surgery. Aphakic eyes had a significantly greater incidence of long term postoperative glaucoma than phakic eyes (P .05). Further examination of the seven aphakic nonglau­comatous eyes that developed glaucoma on long term follow-up showed that 2 were steroid responders, and the remaining five had either vitrectomy, anterior chamber reconst­ruction, cataract extraction, pseudophakos removal or combination of these.

Anterior Vitrectomy

In the 56 aphakic eyes, 28 eyes underwent vitrectomy whereas 28 eyes did not.

In the 28 eyes with vitrectomy, 9 eyes had glaucoma, preoperatively and continued to have it postoperatively. An additional five eyes had early increases in intraocular pressure but only two of these eyes continued to have elevated pressure on long term follow-upfor a total of 11 eyes. In the 28 eyes without vitrectomy. four eyes had preoperative glaucoma and continued to have in postoperatively. An additional four eyes developed both early and late elevation of intraocular pressure for a total of 8 eyes.

The difference in these two groups was not statistically significant.

Suture Technique

Interrupted sutures were in 19 eyes and running sutures in 61 eyes. Preoperatively, glaucoma was present in five (26%) of the former group and 12 (20°0) of the latter group. All these eyes continued to have elevated pressures postoperatively. Five additional eyes in the interrupted suture group and six eyes in the running suture group developed elevated pressures postope­ratively. These elevations were seen both in the early and last postoperative periods. There was no significant difference in the incidence of late postoperative glaucoma between these two groups.

Graft size

Sixty one eyes had donor buttons 0.5mm larger than the host bed while 19 eyes had the same size donor button and host bed. Preoperatively, elevated pressures were present in 14 (23%) of the disparate size grafts and three (16%) of the same size grafts. Postoperatively eyes with disparate size grafts had a slightly higher incidence of glaucoma. There were twenty-one eyes (34%) with early pressure elevations and 19 (31 %) with late elevations. In comparation there was little change in the incidence of elevated pressures in the group with same size donor buttons and host beds. Four of these (21 %) had pressure elevations in both the early and late postoperative periods.


  Discussion Top


We undertook the present study in order to examine the long term incidence of glaucoma after keratoplasty. While short term increases in intraocular pressure are important, we feel that it is the continued elevation of pressure over the long term that presents a major source of morbidity following this procedure.

It has been well known for some time that eyes which are aphakic following kera­toplasty have a higher incidence of glaucoma than eyes which are phakic following keratoplasty[2],[8]. Our analysis of 80 eyes has yielded similar results. There are several factors which may contribute to this increased incidence. In our study, phakic eyes under­going keratoplasty alone, were younger

(average age 48 years) than eyes who were aphakic followin keratoplasty (average age 64 years). The former group also had a lower incidence of preoperative glaucoma than the latter (11% versus 26%). Finally, there is more manipulation of eye structures and hence more inflammation associated with surgery on eyes which are aphakic following keratoplasty. (e.g. lens extraction, anterior vitrectomy, anterior chamber reconstruction, etc).

The relationship between donor button size and host bed size has also been the subject of several studies[2],[6],[8]. A donor button 0.5mm larger than the host bed has been shown to be associated with a lower inci­dence of post operative glaucoma[2],[6]. Some authors[3],[4] have felt that using a donor button that is similar in size to the host bed causes angle distrotion and compression and may be the reason for elevated pressures following keratoplasty. Our data does not support this view. We found no statistical difference in the incidence of postoperative glaucoma when disparate size grafts were compared with same size grafts. This was true even for the subgroup of postoperative aphakic eyes and for those postoperative aphakic eyes without pre-existing glaucoma. These are consistent with previous reports[9].

Suture technique is another factor that has been felt to be related to postoperative increases in intraocular pressure through tissue compression and angle distortions[3],[4],[7]. It is difficult to consistently standardize surgical techniques. All the patients in this series were operated upon by on surgeon (VSN) in the similar fashion. Deep, but not through and through sutures using 16 bites with enough tightening to provide adequate wound closure and without inducing signifi­cant tissue compression were used. Using this technique our overall success rate of clear grafts was 95°,0. We compared the incidence of postoperative glaucoma when interrupted sutures or running sutures were used. There was no statistically significant difference between the two groups.

The presence of glaucoma (< 21 mm Hg) prior to surgery was the one factor that was consistently related to its presence postopera­tively. This relationship held for the entire group of 80 eyes as well as for the subgroup of aphakic eyes. Fifteen eyes (88°0) of the eyes with glaucoma preoperatively continued to have it postoperatively, while only 8 eyes (13%) of the eyes without preoperative glaucoma developed it postoperatively. This difference is statistically significant at P <.001.

While results similar to ours have been previously reported[8],[10], dissimilar findings have also been noted[1],[2],[11],[12]. subThese differen­ces could be related to variations in popula­tion groups of surgical technique, including suture depth, number of suture bites, and degree of suture tightening.

It is possible that changes in the iridocor­neal angle might influence aqueous outflow and intraocular pressure. This might explain the incidence of postoperative glaucoma in nonglaucoematous eyes undergoing keratop­lasty. While 3 of these eight eyes were steroid responders, the other 5 underwent complicated keratoplasties with lens extrac­tion, vitrectomy, and anterior chamber reconstruction. In these eyes changes in the anterior segment, complicated surgical procedures, and increased postoperative inflammation could be the factors underlying postoperative pressure elevations.

Although aphakic eyes had significantly increased incidence of postoperative glaucoma when compared to phakic eyes, we could not identify a particular subgroup within these eyes that was at a greater risk for developing a postoperative elevation of intraocular pressure. Eyes undergoing anterior vitrectomy anterior chamber reconstruction, and/or cataract extraction in addition to keratoplasty did not demonstrate a statistically significant increase in postoperative glaucoma. None the less, a high incidence of postoperative pressure elevations was seen in these groups, each having approximately a 33% incidence of persistent glaucoma. Our data is at variance with previous reports which indicate that combined procedures are associated with a significantly higher incidence of glau­coma[1],[2],[8],[9].

Eyes undergoing reoperations were examined separately. Three eyes (75%) had glaucoma preoperatively and continued to have it postoperatively. While no statistical conclusions can be made from this small number, other studies have previously shown similar data[8].

What all these findings suggest is that performance of more than a simple keratop­lasty and/or cataract extraction carries an increased risk for the development of posto­perative glaucoma. Underlying this may be an increase in inflammation and more distortion of the anterior segment anatomy when complex procedures are performed. Early as well as chronic elevations of posto­perative intraocular pressure remain a problem in many eyes undergoing more than just a simple keratoplasty and/or cataract extraction. Disparity in graft host-relation­ships, suture techniques, pseudophakia, and lens extraction alone were not related to the presence of postoperative elevations of intraocular pressure.

There are few studies of long terms pressure elevations following keratoplasty. However it is this chronic elevation which is the cause of significant ocular morbidity and is an important underlying factor in the poor visual acuity which not infrequently follows successful keratoplasty with an opti­cally clear graft.

 
  References Top

1.
Irvine AR, Kaufman HE., 1969, Amer. J. Ophthalmol. 68 :835.  Back to cited text no. 1
    
2.
Zimmerman T, Olson R, Waltman S, Kaufman H., 1978, Arch Ophthalmal. 96: 2231.  Back to cited text no. 2
    
3.
Olson RJ., 1978, Arch Ophthalmol 96: 2274.   Back to cited text no. 3
    
4.
Olson RJ, Kaufman, HE., 1977, Invest. Ophthalmol. Visual Sci 66: 1085.  Back to cited text no. 4
    
5.
Bourne, WM, Davison JA, O' Fullon WM. 1982, Ophthalmology 89 :242.  Back to cited text no. 5
    
6.
Foulks GN, Perry HD, Dohlman CH, 1979, Ophthalmology 86 : 490-4.  Back to cited text no. 6
    
7.
Zimmerman TJ, Krupin T, Grodzki W, Waltman SR. 1978, Arch Ophthalmol 96: 505.   Back to cited text no. 7
    
8.
Goldberg DB, Schanzlin DJ, Brown SI , 1981, Amer J, Ophthalmol 92 : 372.  Back to cited text no. 8
    
9.
Perl, T, Chariton, KH, Binder. P.S, 1981, Ophthalmology 88 :774.  Back to cited text no. 9
    
10.
Olson, R.J, Kaufman HE., 1978, Amer. J. Ophthalmol. 86: 510.  Back to cited text no. 10
    
11.
Wood To, West C, Kaufman HE., 1972, Amer. J. Ophthalmol. 70-24.  Back to cited text no. 11
    
12.
Thoft RA, Gordon JM. Dohlman Claes H. 1974, Trans. Amer. Acad Ophthalmol 78: 352.  Back to cited text no. 12
    



 
 
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