Hyperopic shift following corneal graft rejection in a patient with keratoconus: A case report

doi:10.21203/rs.3.rs-2739414/v1

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Case Report

Hyperopic shift following corneal graft rejection in a patient with keratoconus: A case report

https://doi.org/10.21203/rs.3.rs-2739414/v1

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Background

Penetrating keratoplasty (PK) is the dominant technique for visual restoration of corneal blindness worldwide. Corneal graft rejection and refractive errors are common postoperative issues of it, but correlation between these complications was seldom reported. To the author’s knowledge, this is the first reported case describing hyperopic change following post-penetrating keratoplasty graft rejection.

Case presentation

A 15-year-old female undergoing PK for advanced keratoconus in the left eye. Postoperatively, the graft was clear and her corrected distance visual acuity (CDVA) improved to 20/20. Corneal topography revealed anterior chamber depth (ACD) of 5.87 mm and keratometry readings of 42.4/46.1 diopters (D). However, decreasing visual acuity to counting fingers was noted after twelve months. Slit-lamp biomicroscopic examination showed stromal edema and mutton-fat keratic precipitates infiltration. Corneal graft rejection was diagnosed and CDVA resumed to 20/20 within one month after intensive topical and high-dose systemic steroid administration. Four years later, corneal topography revealed an ACD of 2.98 mm and keratometry readings of 42.4/45.1 D with spherical equivalence of + 1.25 D. Clinically and topographically, the corneal graft demonstrated a process of flattening before and after the episode of graft rejection.

Conclusions

Graft rejection may cause hyperopic shift in patients with keratoconus after PK.

keratoconus

penetrating keratoplasty

corneal graft rejection

hyperopic shift

anterior chamber depth

Keratoconus is a non-inflammatory corneal disorder characterized by progressive thinning and ectasia of the cornea. Such thinning distorts the contour of the cornea and causes a cone-like bulge to develop. The pathological change of the cornea results in an irregular astigmatism and decreased in visual acuity.

Management of keratoconus includes spectacles and contact lens use, corneal collagen cross-linking, intrastromal corneal ring segment, therapeutic excimer laser and corneal transplantation. In most cases, astigmatism can be corrected by rigid gas-permeable contact lenses. However, some cases require PK because of contact lenses intolerance, poor visual acuity with contact lenses, marked irregular astigmatism, corneal scarring or advanced keratoconus with corneal opacities. The percentage of patients with keratoconus requiring PK varies from 15%-60%, depending on the severity of the disease.(1) PK has been successfully used for visual rehabilitation in keratoconus, with reasonably good visual outcomes,(2, 3) graft survival rate(2, 3) and long-term prognosis.(2) Several studies have shown that more than 73% of patients achieve best-corrected visual acuity of 20/40 or greater after the operation.(3, 4) Therefore, keratoconus is amongst the best indications for performing PK, with long-term graft survival rates better than those of other indications.(4)

During the postoperative PK comes with various complications, including graft rejection, infectious keratitis, glaucoma, suture-related problems, wound leaks, fixed dilated pupils and epithelial defects.(5) One of the postoperative complications worth to be mentioned is graft rejection, which is still the leading cause of graft failure.(6) Various studies have reported on the risk factors and occurrence of corneal graft rejection.(5, 6) Common symptoms of graft rejection include decreased vision, redness of the eyes, light sensitivity, eye discomfort or pain. Manifestations of graft rejection include cornea edema, cellular infiltration, anterior chamber flare, Khodadoust line and keratic precipitates on transplant endothelium.(5) Although rejection events in any cellular layer of the cornea was elaborately described before,(5) the impact of corneal graft rejection on refractive change was rarely reported. The majority of refractive errors were discussed separately from graft rejection in previous studies,(3, 4) and some of those eyes even required refractive surgery for visual correction.(7) Herein, we report an uncommon case of a keratoconus patient presenting with hyperopic shift regarding graft rejection after PK, despite with improved visual acuity after topical and systemic steroid administration.

A 15-year-old female patient was regularly followed at our ophthalmologic clinic because of keratoconus for three years, with best spectacle-corrected distance visual acuity 20/50 in the right eye and 20/400 in the left eye at the first visit (Fig. 1). Rigid gas-permeable contact lenses were applied initially for visual rehabilitation.

Nevertheless, the patient visited our clinic with deteriorating visual acuity of counting fingers at 60 cm two years later. Slit-lamp biomicroscopic examination revealed Vogt’s striae and positive Munson’s sign in both eyes (Fig. 1A). Advanced keratoconus was diagnosed with the aid of computerized corneal topography (Orbscan II, Bosch & Lomb, Salt Lake City, UT, USA). Her corneal topography revealed flat and steep keratometry readings of 49.6 and 50.9 D, astigmatism of 1.3 D, ACD of 2.04 mm, and thinnest corneal thickness of 269 µm (Fig. 1B). Therefore, PK was registered and performed 2 months later for visual rehabilitation. Intraoperatively, the diameter of donor button and host incision were 8.5 mm and 8.0 mm, respectively. In addition, the donor button was sutured onto recipient corneal bed with 10 − 0 nylon for 16 stitches.

Postoperatively, the patient was followed every month without complications such as keratitis, wound leak, suture loosen, and elevated intraocular pressure identified. Six months after keratoplasty, the corneal graft was clear with 16 interrupted stitches and CDVA improved to 20/20 (− 0.50–1.50 X 5) in the left eye (Fig. 1C). Her corneal topography revealed flat and steep keratometry readings of 42.4 and 46.1D, astigmatism of 3.7 D, ACD of 5.87 mm, and thinnest corneal thickness of 464 µm (Fig. 1D).

However, she started having a complaint of blurred vision and foreign body sensation after twelve months. Slit-lamp biomicroscopic examination showed marked stromal edema and mutton-fat keratic precipitates infiltration in the left eye, leading to a clinical diagnosis of corneal graft rejection (Fig. 2A). Her visual acuity dropped to counting fingers at 20 cm, while the corneal topography revealed ACD of 2.97 mm and thinnest corneal thickness of 572 µm (Fig. 2B). Hence, intensive topical and high-dose systemic steroid were administered, resulting in gradual resolution of stromal edema and keratic precipitates infiltration in one week. One month after graft rejection, the corneal graft cleared up and CDVA resumed to 20/20 (+ 2.50–2.25 X 155) in the left eye. Additionally, fourteen sutures were removed due to exposed stitch knots with intolerable tingling sensation after rejection episode. Four years after graft rejection, the corneal graft remained clear with two residual sutures at 4 to 5 o’clock and CDVA remained 20/20 (+ 2.50–2.50 X 55) in the left eye (Fig. 2C), while corneal topography revealed flat and steep keratometry readings of 42.4 and 45.1D, astigmatism of 2.7 D, ACD of 2.98 mm, and thinnest corneal thickness of 515 µm (Fig. 2D).

In summary, the corneal topography before and after graft rejection manifested flattening of transplanted cornea surface. ACD declined from 5.87 mm to 2.98 mm, while maximum simulated keratometry values decreased from 46.1D to 45.1D. During the postoperative period, a hyperopic shift after corneal graft rejection was found.

Little is known regarding the clinical correlation and mechanistic insights of refractive error after corneal graft rejection. To our knowledge, this is the first case report describing hyperopic change following post-penetrating keratoplasty graft rejection.

Increase in ACD from 2.04 to 5.87 mm was found after PK in our case. It is known that postoperative ACD values may differ owing to the diameter differences between donor and recipient bed and the tightness of sutures after PK (8). High diameter differences between donor and recipient bed may cause a steepened graft and a postoperative increase in ACD values, whereas the suture tightness may cause a flattened graft and a postoperative reduction in ACD values. In our case, the graft’s diameter was 8.5 mm and recipient bed’s diameter was 8.0 mm. On the other hand, Buzard et al. used 8.25 mm graft diameter and 8.0 mm recipient bed diameter.(9) Six months after keratoplasty, 16 interrupted sutures were remained with ACD of 5.87 mm. In our report, large change in ACD may be caused by relatively higher diameter differences between donor and recipient bed and subtle loosening of the sutures. Additionally, curvature change due to weaker stromal rigidity after graft rejection was also a possible cause.

Despite relative immune privilege of the cornea, allograft rejection remains the leading cause of corneal graft failure worldwide.(6) In a previously thin and transparent graft, rejection can develop with edematous change and show signs of immunologic reactions, such as corneal infiltrates, keratic precipitates, advanced corneal edema or a rejection line.(3) Our case presents with stromal edema and mutton-fat keratic precipitates infiltration, which are classified into endothelial rejection. Will such a rejection cause following refractive change? Histologically, Polack noticed a replacement in the endothelium with flattened cells in rabbit models.(10) Yenerel et al. observed stromal swelling and undulation of posterior corneal surface in three eyes with acute graft rejection by using anterior segment optical coherence tomography.(11) The case reported by Vignapiano et al. presented with irregular posterior surface of cornea after transplant rejection.(12) Graft rejection appears to be relevant to refractive shift due to changes in corneal surface.

Ametropia is also commonly reported after PK. The visual outcome of corneal transplantation is often devastated by high degrees of astigmatism, which is usually affected by multiple factors such as disease severity, graft size, trephination and suturing technique.(7) Although there is a high prevalence rate of astigmatism after PK, eye conditions related to hypermetropia during postoperative period are less commonly reported, much less to be identified in post-rejection manifestation. Besides, change in manifest refraction spherical equivalent from − 0.50 to + 2.50, whereas change in keratometry from 46.1 D to 45.1 D were observed in our report. Rosenblatt et al. proposed that an increase in magnitude of refractive error was correlated to lower keratometry values in hyperopia.(13) In addition, AlMahmoud et al. reported that keratometry increased by 0.11 D for every diopter of decrease in refractive error across the entire range of refractive error.(14) Our case had more change in keratometry compared to previous study and possible changes in posterior corneal surface should be considered. Since our case presents with endothelial rejection, graft rejection may induce irreversible hyperopia through changes in the posterior corneal curvature due to regenerative incapability in endothelium.

For patients whose PK is performed at relatively young age,(2) postoperative spectacles or contact lens wearing, and even another excimer laser treatment may be required for residual refractive errors(8); therefore, surgeons must discuss following plan and possible complications with patients to optimize long-term outcomes and patient satisfaction. Not only graft failure, endothelial rejection may also be associated with postoperative refraction shift due to its regenerative incapability. While our case offers more insight into the correlation between refractive change and immunologic corneal rejection, further investigation in posterior corneal change after graft rejection to support our hypothesis is still awaited. In summary, our report demonstrates that graft rejection may cause hyperopic change in patients with keratoconus after PK.

Penetrating keratoplasty

CDVA

Corrected distance visual acuity

ACD

Anterior chamber depth

Ethics approval and consent to participate

The study was approved by the Institutional Review Board of Chang Gung Memorial Hospital (Approval No.: 202200767B0) and followed the tenets of the Declaration of Helsinki.

Consent for publication

Written informed consent for publication of their clinical details and/or clinical images was obtained from the patient parent.

Competing interests

The authors declare that they have no competing interests.

Availability of data and materials

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Funding

This study was supported by grants from Chang Gung Memorial Hospital (CRRPG3M0071) and the Ministry of Science and Technology (MOST 107-2314-B-182A-088-MY3) to Chen HC.

Authors’ Contributions

Conceptualization, Cheng Y.F. and Chen H.C.; methodology, Liu C.F. and Meir Y.J.; validation, Hsiao C.H. and Ma D.H.; formal analysis, Liu C.F. and Chen H.C.; investigation, Chen H.C.; resources, Meir Y.J. and Hsiao C.H.; data curation, Liu C.F. and Ma D.H.; writing—original draft preparation, Cheng Y.F. and Chen H.C.; writing—review and editing, Cheng Y.F.; visualization, Chen H.C.; supervision, Chen H.C.; project administration, Chen H.C.; funding acquisition, Chen H.C. All authors have read and agreed to the published version of the manuscript.

Acknowledgements

Not applicable.

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No competing interests reported.

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Hyperopic shift following corneal graft rejection in a patient with keratoconus: A case report

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Background

Case Presentation

Discussion And Conclusions

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