Corneal endothelium in penetrating keratoplasty

Specular microscopy of endothelium after corneal transplantation has often shown a sharp reduction in its number density immediately after surgery and long-term cell loss during the next three to four years in addition to continuous morphologic changes. We examined flat preparations of the endothelium of three corneal buttons removed three weeks, eight weeks, and 11 months after penetrating keratoplasty and compared them to similar preparations from the corneal rims of the respective donors. We did not find significant morphologic changes, and direct endothelial cell counts disclosed an endothelial cell loss of 3.8% at three weeks, 2.6% at eight weeks, and 5.6% at 11 months after keratoplasty. We believe the lack of endothelial cell loss and absence of morphologic changes in these specimens are direct results of our surgical technique.     

Corneal wound dehiscence after penetrating keratoplasty

PURPOSE: To describe the clinical features of corneal wound dehiscence after penetrating keratoplasty (PK) after trauma and suture removal. METHODS: A retrospective review of all eyes needing resuturing in the 5-year period of July 2000 to June 2005 was performed. In total, 76 eyes of 76 patients needed wound resuturing. The indications were early wound leak, wound dehiscence, broken suture, or loose suture. In 29 of the 76 cases, the indication for resuturing after PK was wound dehiscence. Of these, 19 were caused by trauma, and in 10 eyes, dehiscence shortly followed suture removal. RESULTS: The interval between original PK and traumatic wound dehiscence caused by trauma ranged from 15 days to 33 years. In 5 eyes, it was >15 years. Nine eyes (47%) with traumatic dehiscence had final visual acuity better than 6/60, whereas 8 eyes (80%) with suture removal dehiscence had final visual acuity better than 6/18. Most of the dehiscence in the traumatic group was located in the inferior 2 quadrants, in contrast to temporally in the postsuture removal group. The time interval between PK and suture removal in the postsuture removal group was 16 +/- 4 months, and 7 (70%) patients had a continuous suture. Post-suture removal dehiscence was more common when corneal edema was the indication for grafting. CONCLUSIONS: Eyes with traumatic wound dehiscence have worse visual outcome than those with dehiscence after suture removal. Patients should be cautioned about the risks and consequences of wound dehiscence. The suture may be left in place longer in older patients or when corneal edema is the indication for grafting.     

穿透性角膜移植术后植片松线重缝的临床研究

目的 探讨穿透性角膜移植术(penetrating keratoplasty,PKP)后因松线而进行植片重缝的时间及不同原发病的差异、手术前后角膜散光的变化.方法 对2004年1月至2006年6月我院PKP术后行植片重缝的41例(41眼)患者进行随访,其中男28例(28眼)、女13例(13眼);统计PKP术后行松线重缝的原发病、时间及散光变化.结果 松线重缝时间发生于术后1～4个月,感染性角膜病组(真菌性角膜炎、单纯疱疹性病毒性角膜炎、细菌性角膜炎)多发生于术后1个月内,平均为术后(24±10)d.非感染性角膜病组(圆锥角膜、粘连性角膜白斑、Fuchs角膜内皮营养不良、碱烧伤)多发生于术后3个月内,平均为术后(68±36)d.重缝后植片回复平整,上皮愈合.角膜散光平均减少3.74 D.结论 PKP术后3个月内植片重缝可以防止植片翘起,显著降低角膜散光.     

Corneal endothelium after deep anterior lamellar keratoplasty and penetrating keratoplasty for keratoconus: a four-year comparative study

Purpose:

To compare the status of corneal endothelium and central corneal thickness within the first four postoperative years after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) in patients with keratoconus.

Materials and Methods:

Thirty-nine eyes (Group A) which had PK and 44 eyes (Group B) which had DALK for the treatment of keratoconus were included in this retrospective study. The endothelial cell density (ECD), the mean endothelial cell area and the coefficient of variation of cell area were assessed with a non-contact specular microscope, and the central corneal thickness (CCT) was measured with an ultrasound pachymeter.

Results:

Mean ECD loss rate at two years was 36.24% in Group A and 18.12% in Group B (P<0.001). Mean ECD loss rate at four years was 47.82% in Group A and 21.62% in Group B (P<0.001). Mean annual ECD loss rate was calculated 14.12% per year in Group A and 5.78% per year in Group B. In the PK group, increase in mean CCT was 15.60% in two years and 15.03% in four years, while in the DALK group, mean CCT increased by 8.05% in two years and 9.31% in four years.

Conclusions:

As the majority of ectatic disorders such as keratoconus occur in young people, long-term endothelial cell survival following treatment with keratoplasty is essential for the long-term visual ability. Our finding that corneal endothelial cell loss in the DALK group occurs at a slower rate than in the PK group suggests DALK as a safer alternative to PK in these selected patients.     

Corneal dioptric power after penetrating keratoplasty.

The dioptric power of the cornea (spherical equivalent) was studied in 60 eyes operated on for penetrating keratoplasty. In order to determine the possible influence of (1) the underlying pathology, (2) the presence of neovascularisation, or (3) the size of the graft the sample was divided into four groups, with the following results: group A (keratoconus, same-sized graft) = 42.25 D; group B (keratoconus, oversized graft) = 45.16 D; group C (keratopathy with minimal or no vascularisation) = 45.34 D; group D (keratopathy with significant vascularisation) = 45.36 D. The results showed that donor-receptor disparity is the main factor determining the outcome of the postoperative corneal spherical power. There was no demonstrable influence from underlying pathology or the presence of vessels in the receptor cornea.     

Corneal topographic results after eccentric,biconvex penetrating keratoplasty

PURPOSE: To study the surgical outcomes and postoperative corneal topographies in 5 patients who had eccentric, biconvex penetrating keratoplasty (PKP) for peripheral corneal disorders whose extent did not allow the use of round grafts without involving the center of the cornea. SETTING: 1st Department of Ophthalmology, Semmelweis University, Medical School, Budapest, Hungary. METHODS: Eccentric, biconvex PKP that spared the optical axis of the cornea was performed in 5 eyes. Indications for surgery were perforated peripheral ulcerative keratitis (n = 3), extensive infiltrated peripheral ulcerative keratitis with impending perforation (n = 1), and ulcerated corneal degeneration caused by an intracameral foreign body for 9 years (n = 1). Computer-assisted corneal topography was performed postoperatively. The follow-up ranged from 8 to 27 months. RESULTS: All grafts were tectonically effective. Postoperative corneal topography showed normal central corneal regularity in 4 cases (1 case, normal pattern with surface regularity index [SRI] and surface asymmetry index [SAI] within the normal range; 3 cases, normal surface regularity within the central area of the cornea but moderate or high central corneal asymmetry). One eye had irregular astigmatism with a high SRI and SAI. In the first 4 cases, the best spectacle-corrected visual acuity was 0.8 (20/25) or better. CONCLUSIONS: The results show that eccentric, biconvex PKP sparing the central cornea may be an option in some eyes with perforated peripheral corneal disorders. Postoperative visual acuity may be good as the procedure may result in a regular central anterior corneal surface.     

Corneal steepening with final suture removal after penetrating keratoplasty

We reviewed 53 patients after they underwent penetrating keratoplasty, comparing the change in average corneal curvature before and after final suture removal 15-18 months postsurgery. In 29 eyes with keratoconus, there was a significant increase in average curvature of 3.48 diopters +/- 3.76 (p less than 0.0005). In 24 eyes with other diagnoses, there was also a significant increase in the average curvature of 3.26 diopters +/- 3.98, (p less than 0.0005). The difference between these groups was not significant. The amount of steepening correlated negatively (-.6494) with the average corneal curvature before suture removal (p less than 0.005). We found no change in the average astigmatism after suture removal; however, large changes in astigmatism occurred unpredictably with some patients. This study shows that corneal curvature after penetrating keratoplasty steepens after suture removal, particularly in flat corneas, and astigmatism may shift unpredictably.     

Corneal lamellar flap retraction after LASIK following penetrating keratoplasty

PURPOSE: To describe a case of lamellar flap retraction after laser in situ keratomileusis (LASIK) to correct myopia and astigmatism after penetrating keratoplasty (PKP). METHODS: Eleven months after PKP, a 34-year-old man underwent uneventful LASIK. Preoperative manifest refraction was -5.50 + 4.00 x 55, giving a best-corrected visual acuity (BCVA) of 20/20. Three days after LASIK, the central cornea was clear with a 1- to 2-mm displacement and marked swelling of the inferior edge of the lamellar corneal flap, without central striae. The patient's uncorrected visual acuity (UCVA) was 20/60. The flap was repositioned, sutured with 6 10-0 nylon interrupted sutures, and covered with a bandage contact lens. RESULTS: Five months after the repair, the cornea was clear, UCVA was 20/400, and manifest refraction was -9.50 + 6.00 x 75, giving a BCVA of 20/60. Three years later, manifest refraction was - 9.00 + 4.00 x 70, giving a BCVA of 20/40+2. CONCLUSION: In LASIK surgery after PKP, there is a risk of flap edema leading to retraction of the transplant wound. It may therefore be advisable to wait at least 1-2 years after PKP before performing LASIK. Patients who have corneal transplants should also be warned that they might have unique risks in LASIK treatment that may result in the loss of vision.     

Corneal topography for selective suture removal after penetrating keratoplasty

Twenty-nine suture removals from 20 eyes (21 patients) on which penetrating keratoplasty had been performed were analyzed in a nonrandomized consecutive study to evaluate the role of computer-assisted corneal topography in selective suture removal to reduce astigmatism. Topographic guidance for suture removal resulted in a net decrease in refractive and keratometric astigmatism in 21 of the 29 cases. The net reduction in astigmatism averaged 1.4, 0.9, and 1.0 diopters when measured by refraction, keratometry, and topography, respectively. The preliminary choice of sutures to be removed on the basis of refraction, keratometry, and inspection was changed in 20 of the 29 cases when information added by the topographic map was considered. Although many variables of suture removal remain unpredictable, computer-assisted corneal topography is a powerful means of describing corneal power after penetrating keratoplasty and is useful as a guide in selective suture removal for reduction of astigmatism.     

Corneal epithelium following penetrating keratoplasty.

AIMS--This study was designed to observe any changes to the corneal epithelium after penetrating keratoplasty. METHODS--The corneal epithelia of 26 patients were observed by specular microscopy 1 week, 1 month, 3 months, and 6 months following penetrating keratoplasty. RESULTS--After re-epithelialisation was confirmed by biomicroscopy 1 week after surgery, specular microscopy revealed many abnormal cells, including spindle shaped cells, nucleated cells, large cells, as well as irregular cell configurations. Although these abnormal findings tended to decrease with time, they were still present in some cases as much as 6 months postoperatively. Computerised morphometric analysis yielded mean cell areas of 1121 (SD 168) microns 2, 1139 (675) microns 2, 1712 (496) microns 2, and 1400 (377) microns 2 at 1 week, 1 month, 3 months, and 6 months respectively, all significantly greater than that of age matched controls (710 (151) microns 2). The shape factor decreased with time, but was still greater than the control level at 6 months. CONCLUSIONS--This study demonstrates that epithelial abnormalities persist longer than expected after penetrating keratoplasty, and that these subtle changes can be detected by specular microscopic observation, potentially allowing for modification and enhancement of the wound healing process.     

Corneal topography of transverse keratotomies for astigmatism after penetrating keratoplasty

We used a topography system to evaluate retrospectively the pattern of power distribution seen preoperatively and postoperatively in six patients with high postkeratoplasty astigmatism. The relaxing incisions had all been placed based on visual inspection of keratoscope mires alone. Computer analysis of keratoscope photographs showed considerable individual variation in the degree of surface irregularity in preoperative topography. Our data suggest that the steep axis of the postkeratoplasty graft is better conceptualized as two steep hemimeridians. These hemimeridians were separated by an angle other than 180 degrees (two of six cases), and often showed fairly large changes in power from the most central to peripheral areas of the graft analyzed (three of six cases). Asymmetry of power between the two steep hemimeridians was seen in all cases. Areas of maximum steepening were often present in the peripheral portions of the graft in areas other than the major hemimeridians. Individual variation in preoperative corneal irregularity and asymmetry appeared to have an effect on the success of the relaxing incisions.     

Corneal radius of curvature after anterior lamellar versus penetrating keratoplasty

Background

Keratoplasty may induce major spherical refractive error related to abnormal corneal radius of curvature (CRC).

Methods

Two hundred and thirty-eight consecutive eyes of 238 patients with clear graft and at least one postoperative Orbscan examination performed after suture removal (average follow-up time, 86 months) were retrospectively analyzed. Anterior lamellar keratoplasties (ALK group, n?=?119) and penetrating keratoplasties (PK group, n?=?119) were matched for preoperative diagnosis and lens status.

Results

The average postoperative, suture-out, Orbscan 3-mm CRC was 7.17 mm with a wide 95 % confidence interval [6.26 mm; 8.37 mm]. It was 7.05 mm in the ALK group and 7.31 mm in the PK group (p?<?0.01). In the ALK group, this figure was 7.00 mm for oversized grafts and 7.67 mm for non-oversized grafts (p?<?0.001). CRC values were significantly lower for eyes with keratoconus (7.00 mm) or stromal scar after infectious keratitis (7.06 mm) compared with stromal scar after trauma (7.74 mm) or stromal dystrophies (8.17 mm). Values were significantly lower for big-bubble ALKs (6.92 mm) and manual dissection-ALKs (7.14 mm) compared with PKs (7.31 mm) and microkeratome-assisted ALKs (7.45 mm). The average Orbscan 3-mm SimK cylinder, irregularity, and refractive power symmetry index were, respectively, 4.7 D/4.8 D/1.9 D for ALKs and 5.2 D/4.8 D/1.8 D for PKs (p?=?0.99).

Conclusions

The CRC is lower after ALK compared with PK, and features important variability. In eyes with ALK, non-oversized grafts result in postoperative CRC close to normal values and corneal diseases associated with stromal thinning and DALK result in lower postoperative CRC.