Safety of DSAEK in patients with previous glaucoma filtering surgery

Abstract

Purpose

To report four cases of Descemet stripping automated endothelial keratoplasty (DSAEK) in the presence of previous glaucoma filtering surgery.

Design

Observational case series.

Methods

Review of clinical data of four patients who underwent DSAEK successfully performed in the presence of previous glaucoma filtering surgery with endothelial survival rates comparable with larger series previously published and good postoperative IOP control.

Results

The endothelial cell loss was 36% and 39% mean cell loss at 6 months and 1 year postoperatively. The intraocular pressure remained well controlled within target levels in all patients. No complications were reported in any of the 4 cases.

Conclusions

Corneal endothelial failure can be successfully managed with DSAEK in glaucoma patients with previous filtering surgery with good endothelial survival rates and good IOP control.

Descemet stripping automated endothelial keratoplasty (DSAEK) has recently gained popularity as the procedure of choice in the management of corneal endothelial disease. The advantages of DSAEK over penetrating keratoplasty (PK) include the avoidance of open sky surgery, minimal induced post-surgical astigmatism and faster visual rehabilitation (1, 2). Theoretically, DSAEK performed in patients with history of previous filtering procedures may reduce the rate of intraoperative complications previously reported after conventional PK. However the presence of a fistula in these eyes may not allow the intraocular pressure (IOP) to reach the level necessary to achieve attachment of the donor graft to the posterior corneal surface. We describe four cases of DSAEK successfully performed in the presence of previous glaucoma filtering surgery with endothelial survival rates comparable with larger series previously published (4, 5) and good postoperative IOP control.

Report of Cases

All patients presenting to our institution with pseudophakic bullous keratopathy in the presence of normal IOP following glaucoma surgery were included. Average age was 67 years. Previous glaucoma surgery included trabeculectomy (1 case) and glaucoma shunts (3 cases). All patients were pseudophakic. Surgery was uneventful and graft attachment was achieved in all cases. Postoperatively IOP remained within target levels in all cases with antiglaucoma topical treatment required in 2 cases. No postoperative complications were observed particularly early hypotony or graft dislocations.

Table 1 illustrates the preoperative data and the 6 month and 12 month IOP values and endothelial cell density (ECD) for each patient. As can be seen, the endothelial survival rate is compatible with previous reports that show 34% and 35% mean cell loss at 6 months and 1 year postoperatively (4). No complications were reported in any of the 4 cases.

Table 1.

Preoperative data and 6 month and 12 month IOP and Endothelial Cell Densities of the endothelial graft (cells per square millimeter) after DSAEK

PATIENT	AGE	PREVIOUS GLAUCOMA SURGERY	PREOPERATIVE			POSTOPERATIVE
			IOP	ECD	BSCVA	ECD 6 m	IOP 6 m	ECD 12 m	IOP 12m	BSCVA
1	73	Ahmed	14	2004	20/100	1474	15	1343	15	20/40
2	67	Baerveldt	11	2270	20/80	1645	10	1509	12	20/25
3	59	Baerveldt	14	1901	20/200	1368	14	1269	12	20/50
4	70	Trabeculectomy	12	1872	20/200	1408	14	1325	14	20/50

BSCVA: Best spectacle corrected visual acuity. IOP = intraocular pressure. ECD = endothelial cell density of the corneal endothelial graft.

The surgical technique used was modified as follows: The donor corneal lenticle was prepared using a Moria CB microkeratome head (350 μm blade depth) and had a diameter of 8 mm. Three paracenthesis were performed in the host cornea in the nasal, inferior and temporal quadrants. An irrigating corneal scraper was used to remove the Descemet membrane from the central cornea. A 4mm clear corneal incision was made superiorly. The donor tissue was folded 60% - 40% over Healon and was inserted into the recipient anterior chamber through the superior incision. The corneal disk was unfolded with balanced salt solution and air and was positioned against the recipient bed. The anterior chamber was filled 100% with air for 20 minutes and then 50% of the air was exchanged with BSS. The IOP was measured using Goldman applanation tonometry. The preoperative ECD was measured in the eye bank using an EB-3000 XYZ specular microscope (HAI Laboratories Inc., Lexington, MA). The cell counts were obtained using an apices digitized method and the manufacturer's calibration for magnification. The apices of at least 100 cells from the endothelial images from each cornea were counted. The postoperative ECD were performed by the same certified technician using a SP 9000 non contact specular microscope (Konan Medical Corp., Fair Lawn, NJ). The cell counts were obtained using the manufacturer's calibration for magnification and were counted with a fixed frame method with the protocol reqiering the marking of at least 50 cells for each image.

Comment

Here we report 4 cases of pseudophakic bullous keratopathy with well controlled glaucoma after filtering surgery successfully treated with DSAEK with adequate postoperative IOP control and endothelial survival rates similar to previously described in the literature for DSAEK. In eyes with previous glaucoma filtering surgery early absorption of the air fill in the presence of a fistula may be followed by marked hypotony and consequent detachment of the donor graft. We recommend smaller diameter grafts (8 mm) to prevent touch with the glaucoma tubes, peripheral scrapping as previously described (6) and allowing 20 minutes of complete air fill of the AC intraoperatively (as opposed to 10 in standard cases) before exchange with BSS in order to enhance graft adherence. Further studies with longer follow-up periods should be performed to compare the endothelial cell loss over time in this group as opposed to standard DSAEK patients.

Figure 1.

One month postoperative appearance of DSAEK graft in pseudophakic patient with a glaucoma filtering tube. Best corrected visual acuity is 20/30. Solid arrows indicate edge of DSAEK graft. Dotted arrow illustrates glaucoma tube.