|Year : 2023 | Volume
| Issue : 1 | Page : 42-44
Post-deep anterior lamellar keratoplasty ectasia in a case of macular corneal dystrophy
Deepali Singhal1, Nimmy Raj2, Prafulla K Maharana2
1 Department of Cornea, Cataract and Refractive Surgery, Centre for Sight Eye Hospital, Bhubaneswar, India
2 Department of Ophthalmology, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
|Date of Submission||21-May-2022|
|Date of Acceptance||16-Aug-2022|
|Date of Web Publication||20-Jan-2023|
Prafulla K Maharana
Assistant Professor of Ophthalmology, Cornea, Cataract and Refractive Surgery Services, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi
Source of Support: None, Conflict of Interest: None
A 30-year-old female presented with diminution of vision in the right eye for 2 months. She was a known case of macular corneal dystrophy and had undergone OD deep anterior lamellar keratoplasty 2 years back. The best corrected visual acuity (BCVA) was 6/18 at 6 months. At presentation, the BCVA was 4/60 and 6/60 in OD and OS, respectively. The graft was clear with no interface haze. An area of graft ectasia with thinning at the inferotemporal (7–9'o clock) graft–host junction was noted clinically and on tomography. Rigid gas permeable contact lenses showed a BCVA of 6/9 and were advised.
Keywords: Deep anterior lamellar keratoplasty (DALK), ectasia, macular corneal dystrophy
|How to cite this article:|
Singhal D, Raj N, Maharana PK. Post-deep anterior lamellar keratoplasty ectasia in a case of macular corneal dystrophy. Indian J Ophthalmol Case Rep 2023;3:42-4
|How to cite this URL:|
Singhal D, Raj N, Maharana PK. Post-deep anterior lamellar keratoplasty ectasia in a case of macular corneal dystrophy. Indian J Ophthalmol Case Rep [serial online] 2023 [cited 2023 Feb 1];3:42-4. Available from: https://www.ijoreports.in/text.asp?2023/3/1/42/368129
Recurrent corneal ectasia following penetrating keratoplasty or deep anterior lamellar keratoplasty (DALK) has been described previously in cases of keratoconus (KCN)., Invasion of the graft by host keratocytes that may be metabolically prone to produce abnormal corneal architecture has been proposed to be a factor for recurrent ectasia.
In MCD, central corneal thinning has been previously documented, Though it has been reported to be associated with KCN in some case reports, post-DALK ectasia in a case of MCD has not been described in the literature. Herein, we describe a case of post-DALK ectasia in a case of MCD.
| Case Report|| |
A 30-year-old female presented with complaints of gradual progressive diminution of vision in her right eye for 2 months. There was no history of pain, redness, photophobia, and trauma. She had undergone OD DALK for MCD 2 years back.
On reviewing the old records, the preoperative BCVA was 6/60 and 6/36 in the right and left eyes, respectively. Preoperative central corneal thickness (CCT) was 390 and 430 μm in the right and left eyes, respectively. Corneal topography recorded preoperatively was also normal, with k1/k2 of 45.9/44.2 DD (98°/8°) and 43.8/44.5 D (67°/157°) in the right and left eyes, respectively. Immediate postoperative BCVA was 6/60. MCD was confirmed based on an Alcian blue-stained pathological specimen. BSCVA documented was 6/18 at 6 months follow-up with a refraction of −2 DS/−4 D cylinder at 35°.
On examination, BSCVA was 3/60 in the right eye. The graft was clear. At most of the areas of the G–H junction, the graft thickness was normal but with steep curvature and thin peripheral host stroma [Figure 1]a. However, a localized area of thinning involving the graft and the graft–host (G–H) junction was seen between 7 and 9'o clock with mild protrusion of the graft as shown in [Figure 1]b. The posterior segment was within normal limits. IOP was normal. The left eye showed typical features of MCD [Figure 1]c.
|Figure 1: (a) Clinical photograph of right eye operated deep anterior lamellar keratoplasty (DALK) showing the marked area with a normal graft thickness and a thin peripheral host rim. (b) The marked area corresponding to that shown in corneal tomography [Figure 3] depicts localized thinning of the graft and the graft-host junction between 7 and 9'o clock. (c) Clinical photograph of the left eye showing macular corneal dystrophy|
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RGP contact lens trial showed a BCVA of 6/9 in the right eye. Corneal tomography revealed simulated keratometry k1/k2 of 40.6/52.0 DD (23.50/113.50), kmax of 57.9 D, posterior elevation (PE) of +43.0 D, thinnest pachymetry of 496, and D value of 5.79 in the right eye [Figure 3]. The localized area of thinning of the graft and the G–H junction between 7 and 9'o clock seen clinically correlated with the corneal tomography showing a steep curvature with red color (km = 55.5 D) along with an increased anterior elevation of +88 microns and increased posterior elevation of 28–181 microns and a reduced corneal thickness (496–513 microns) as compared to the other areas of the graft (range: 576–644 microns) [Figure 3]. All these signs suggest a localized thinning with ectasia. In addition, other areas of the G–H junction only show steep corneal curvature with normal thickness and elevation values. Thus, we made a diagnosis of post-DALK ectasia in MCD.
|Figure 3: Corneal tomography image of the right eye shows a localized area (between 7 and 9'o clock) of steep curvature with red color (km = 55.5D) along with an increased anterior elevation of +88 microns, increased posterior elevation of 28–181 microns and a reduced corneal thickness (496–513 microns) as compared to the other areas of the graft (range: 576–644 microns). In addition, other areas of the G–H junction only show steep corneal curvature with a normal thickness and elevation values|
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Anterior segment optical coherence tomography (ASOCT) showed a CCT of 489 and 346 μm in the right and left eyes, respectively [Figure 2].
|Figure 2: ASOCT photograph of the right eye operated deep anterior lamellar keratoplasty (DALK) showing graft ectasia with peripheral thinning of the host stroma|
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The presence of any preexisting keratoconus with MCD was ruled out as preoperative corneal topography was normal (k1/k2 of 45.9/44.2 D (980/80) in the right eye) and good vision gain (6/18) post DALK.
Initially, the patient was advised for refraction in the right eye, but that was not possible due to scissoring of reflex. So, we went ahead with the RGP contact lens trial, which showed a BCVA of 6/9. The patient was prescribed RGP contact lenses and was asked to follow up after 3 months.
| Discussion|| |
Recurrent corneal ectasia following penetrating keratoplasty or DALK has been described previously in cases of keratoconus., Ectasia post keratoplasty is usually preceded by thinning of the recipient's corneal stroma at the graft–host junction, more frequently located inferiorly. In our patient, the peripheral host cornea was already thin due to MCD.
The hallmark of post-keratoplasty corneal ectasia is the presence of focal or generalized thinning with protrusion of the graft–host junction along with gradually reducing BSCVA, increasing km and astigmatism value, and increasing myopic shift developing years after DALK or PK. All these clinical features were present in our patient and pointed toward post-DALK ectasia.
However, to the best of our knowledge, the finding of post-DALK ectasia in a case of MCD has not been described in the literature.
There are two major issues to be discussed in this case. First, why did the patient develop ectasia so early, and second, what is the best approach to manage such cases.
MCD has been reported to be associated with KCN in some case reports. The cause of this association is still unknown. Javadi et al. identified some biochemical similarities between these two disorders such as reduced levels of keratan sulfate and an increased ratio of dermatan to keratan sulfate. They postulated that a biochemical alteration in the size of collagen fibrils along with increased packing of these fibrils due to abnormal deposits in macular dystrophy might contribute to stromal thinning and ectasia in these cases. Balestrazzi et al. reported the presence of highly reflective scar tissue involving the basal membrane to the stroma. They postulated that this might be due to focal rupture of Bowman's membrane that can be seen in both keratoconus and macular dystrophy. In fact, histopathologically, MCD is characterized by focal ruptures of Bowman's membrane in some areas. These causes could explain the association of stromal thinning and ectasia in MCD. Our case also had preexisting stromal thinning involving the peripheral cornea.
Management of such cases is not simple. Post keratoplasty ectasia usually involves the peripheral graft and the hraft host junction, so only performing a regraft will not be adequate since the thin host stroma needs to be supported as well. this can be done by performing Tuck in lamellar keratoplasty or a large diameter LK. Vajpayee et al. have described tuck-in lamellar keratoplasty (TILK) in cases of advanced corneal ectasia with peripheral thinning in which a central lamellar keratoplasty with intrastromal tucking of the peripheral flange of the donor is performed to provide adequate support to the graft–host junction. Other surgical interventions include lamellar horseshoe-shaped sclera-keratoplasty, wedge resection, lamellar keratoplasty with penetrating keratoplasty, crescentic lamellar keratoplasty, and large diameter penetrating keratoplasty. All these procedures are technically challenging and should be resorted to only after nonsurgical methods such as contact lenses (CL) fail. In our case, the BCVA improved to 6/12 with an RGP lens and hence the patient was advised RGP CL and was asked to follow up after 3 months for a repeat evaluation. We would plan to go ahead with TILK if the patient is not tolerant to RGP CL or cannot afford them.
| Conclusion|| |
To conclude, careful preoperative evaluation is extremely important in cases of macular corneal dystrophy to rule out peripheral corneal thinning or associated KCN. If present, peripheral thinning should be tackled carefully at the first surgery, preferably with peripheral tuck-in of the graft. In addition, such cases should be followed up carefully to look for any sign of post-keratoplasty ectasia.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]