the preoperative assessment of the corneal endothelium

Australian and New Zealand Journal of Ophthalmology 1988; 16: 309-316

THE PREOPERATIVE ASSESSMENT OF THE CORNEAL ENDOTHELIUM

ANNE 1111. V. BROOKS YD, FRACO, FRACS, FRACP

GLENYS GRANT AIAP. MWA

The Royal Vctorian Eye and Ear Hospital. East Melbourne

The Royal Victorian Eye and Ear Hospital. East Melbourne

w. E. GlLLlES FRACO. FRACS, FRCS(Ed) The Royal Vctorlan Eye and Ear Hospital, East Melbourne

Abstract The ability of the cornea to maintain its transparency after surgery depends primarily upon the integrity of the corneal endothelium and in corneal grafting this is important for both donor and recipient eyes. The corneal endothe/ium may be signficanUy affected in various conditions of the antem segment, especralfy rf these exist over a considerabfe period of time. These conditions include suptficial keratopathy, long- term contact lens wear, cornea gutfata and low-grade anterior uveitis, especially chronic cyclitis which may be almost imperceptible clinically. The suitability of such corneas for use as donor material as well as the response of the eyes to anterior segment surgery can be assessed by specular microscopy and this may become even more important in the future as long-term contact lens wearers become more numerous in the community.

Key words: Contact lens wear, cornea gutfata, corneal endothelium. corneal graft, specular microscopy, superficial keratopathy, uveitis.

A major factor in securing a successful corneal graft is the quality of the donor material and the major factor in the viability of this donor material is the state of the corneal endothelium.

After storage of graft material there is some oedema and thickening of the donor cornea which makes it difficult to inspect the endothelium.'.' However, if the donor eye is examined immediately after collection, specular microscopy of the endothelium should still be

and if methods of storage are care- fully standardised the photographs obtained Soon after collection should accurately predict the ability of the endothelium to function satis- factorily after transplantation.

It is true that accurate history taking and a careful slit-lamp examination of the donor eye

may enable rejection of many unsatisfactory eyes but endothelial microscopy is more precise. An accurate history may not be easy to obtain in victims of road accidents.

Further, the slit-lamp signs of many conditions associated with a low endothelial cell count or abnormal changes in the corneal endothelium may be quite subtle. This is particularly SO with some cases of superficial keratopathy,' early cornea guttatas and anterior uveitis;." especially chronic cy~ l i t i s , ' ~ - '~ which may have been unrecognised in life. Even the presence of a posterior chamber intraocular lens may be missed, while long-term contact lens wear, hard or soft, may produce marked corneal endothelial

whose significance in corneal grafting is unknown. Elderly patients may have

Reprinf requests: Dr A. M. V. Brooks, 394 Albert Street, East Melbourne, Victoria 3002, Australia.

THE PREOPERATIVE ASSESSMENT OF THE CORNEAL ENDOTHELIUM 309

Figure I : Slit-lamp appearance of a 66-yeardd female with long-standing keratoconjunctivitis sicca. There is a little fluorescein staining of the cornea and mild

conjunctival injection.

a high endothelial cell count but in others it may be too low’*-*’ for safe use as donor material.

Specular microscopy immediately after collection offers a relatively simple and inexpensive method of quality control in keratoplasty.

MATERIALS AND METHODS Specular microscopy was performed using the wide field Pocklington contact specular microscope, following the instillation of topical oxybuprocaine hydrochloride 0.4% and without the use of a contact lens. A Minolta XD-5 camera with data back was attached to the specular microscope. Kodak Plus X Pan 135 film was used and developed with Microphen at 22 “C for 10 minutes using constant agitation. Cell counts were performed using a modification of

Figure 3: Slit-lamp appearance Of a 44-year-old female who had worn hard contact lenses for 19 years

showing the normal appearance of the cornea.

the technique described in the Pocklington manua1.22 A standard grid was pIaced over the 35 mm negative which was viewed using a Medical Viewer GR-8 at eight times magnifica- tion. A multiplying factor of 25 was used in the calculation.

A series of patients is described with little clinical sign of anterior segment pathology on slit-lamp examination but with quite obvious changes on specular microscopy of the corneal endothelium.

CASE REPORTS Case 1 A 66-year-old Caucasian female who was under treatment for long-standing keratoconjunctivitis

Figure 4: Specular microscopy of the same eye as Figure 3. Endothelial cell count 2525 cells/mm’ with moderate pleomorphism and polymegathism. There IS a great variation in cell size with many very small cells and some quite large cells with considerable vari-

ation between areas. Bar = 100 pm.

Figure 2: Specular microscopy of the same eye as Figure 1 shows oedematous blebs and low endothelial cell count of 1725 cells/mm’ with moderate pleo-

morphism and polymegathism. Bar = 100 pm.

310 AUSTRALIAN AND NEW ZEALAND JOURNAL OF OPHTHALMOLOGY

Figure 5: Slit-lamp appearance of a 79-year-old female with cornea guttata showing a virtually normal corneal

appearance.

Figure 6: Specular microscopy of the same eye as Figure 5 showing numerous guttae. Endothelial cell count 1825 cells/mm’ with mild pleomorphism and

polymegathism. Bar = 100 pm.

Figure 7: Specular microscopy of another area of the Same cornea as in Figures 5 and 6 showing a paucity of guttae. Endothelial cell count 2025 cells/mmf with mild pleomorphism and polymegathism. The slightly lower endothelial cell count in Figure 6 is probably due to the influence of the far more numerous corneal

guttae. Bar = 100 pm.

THE PREOPERATIVE ASSESSMENT OF THE CORNEAL E

sicca had only mild superficial keratopathy on slit-lamp examination (Figure 1). However, on specular microscopy there were oedematous blebs which tended to coalesce and the endothelial cell count was reduced (1725 cells/mm*) with moderate pleomorphism and polymegathism of the cells (Figure 2).

Case 2 A 44-year-old Caucasian female who had worn hard contact lenses for 19 years had a normal cornea and anterior segment on slit-lamp examination (Figure 3). However, specular microscopy showed an endothelial cell count of 2525 cells/mm* with moderate pleomorphism and polymegathism (Figure 4).

Case 3 A 79-year-old Caucasian female with clear corneas showed only fine corneal guttae on very careful slit-lamp examination (Figure 5 ) . However, on specular microscopy numerous guttae were seen in some areas (Figure 6) with an endothelial cell count of 1825 cells/mm* and mild pleomorphism and polymegathism. The guttae were not present to the same extent in all areas examined and in other areas only a few guttae were seen (Figure 7).

Case 4 A 51-year-old Caucasian female with cornea guttata. The cornea in the fellow eye had decompensated six years earlier due to Fuchs’ dystrophy. In this less affected eye the corneal guttae were not particularly prominent on slit- lamp examination (Figure 8). On specular microscopy the endothelium was virtually normal in some areas with an endothelial cell count of 2400 cells/mm2 (Figure 9) but in other areas numerous small guttae were seen with an endothelial cell count of 2200 cells/mm’ (Figure 10).

Case 5 A 74-year-old Caucasian female who had mild recurrent anterior uveitis had an eye which appeared normal on slit-lamp examination (Figure 11). However, on specular microscopy there was a reduced endothelial cell count of 1850

31 1 ! N W T H E LI U M

Figure 8: Slit-lamp appearance of a 51-year-old female with cornea guttata showing the normal appearance

of the cornea.

Figure 9: Specular microscopy of the same eye as Figure 8 showing a virtually normal endothelium. Endothelial cell count 2400 cells/mm‘ with mild pleomorphism and polymegathism. Bar = 100 vm.

Figure 10: Spular microscopy of another area of the cornea shown in Figures 8 and 9. There are numerous small guttae. Endothelial cell count 2u)o cells/mm’ with mild pleomorphism and polymegathism.

B a r = l o O ~ .

cells/mm’ with the moderate pleomorphism and polymegathism of the endothelial cells (Figure 12).

Case 6 A 7@year-old Caucasian female who had a posterior chamber intraocular lens in place which was almost undetectable clinically (Figure 13). However, there was a low endothelial cell count of 1050 cells/mm* with moderate pleomorphism and polymegathism (Figure 14). The fellow phakic eye had a relatively normal endothelium for a patient of this age with an endothelial cell count of 2250 celIs/mm’ and a regular mosaic (Figure 15).

Case 7 A 59-year-old Caucasian female who had pseudoexfoliation of the lens capsule and ocular hypertension had pseudoexfoliative material just visible at the pupil margin on slit-lamp examination (Figure 16). The endothelial cell count was 2700 cells/mm2 with a regular mosaic (Figure 17).

Case 8 An 87-year-old Caucasian male with shallow anterior chambers had a rise in intraocular pres- sure on dark room testing and had undergone a prophylactic surgical peripheral iridectomy three years earlier (Figure 18). The endothelium was normal with an endothelial cell count of 2750 cells/mm2 and a regular mosaic (Figure 19).

Case 9 A 69-year-old Caucasian female who had undergone a corneal graft, extracapsular cataract extraction and posterior chamber intraocular lens implant for decompensated Fuchs’ dystrophy had a clear graft (Figure 20). The graft endothelium was normal with an endothelial cell count of 3000 ceils/mmz and a regular mosaic (Figure 21). The unoperated fellow eye with cornea guttata appeared normal on slit-lamp examination (Figure 22) but on specular microscopy there were small guttae and a reduced endothelial cell count of 1225 cells/mm’


Figure I I : Slit-lamp appearance of a 74-year-old female with long-standing low grade anterior uveitis showing the virtually normal slit lamp appearance. Figure 14: Specular microscopy of the same eye as

Figure 13. The endothelial cell count is lOs0 ceUs/mm’ wsh moderate pleomorphism and polymegathism.

Bar = 100 pn.

Figure 12: Specular microscopy of the same eye as Figure I 1 showing large cells with an endothelial cell count of 1850 cells/mrn’ and moderate pleomorphism

and polymegathism. Bar= 100 pm.

Figure IS: Specular microscopy of the unoperated fellow eye with endothelial cell count of 2250

cells/mm* and regular mosaic. Bar = I 0 0 pm.

with mild pleomorphism and polymegathism of the endothelial cells (Figure 23).

DISCUSSION In this small series of miscellaneous cases the anterior segment pathology present would be difficult to detect on a brief post mortem ocular examination. However, specular microscopy shows the grossly abnormal corneal endothelium which often accompanies cases of superficial keratopathy (Case l),’ early cornea guttata (Cases 3 and 4): and anterior uveitis (Case 5).’.’’ In these cases the findings on specular microscow indicate that these corneas are . -

&we 13: Slit-lamp appearance of a 7O-year-old female following extracapsular cataract extraction and

posterior chamber intraocular lens implant. unsuitable for use for corneal grafting. Long- term contact lens wearers (Case 2) constitute a


Figure 18: Sht-lamp appearance of a 87-year-old m& with shallow anterior chamber and surgical peripheral

iridectomy three years earlier. Figure 16: Slit-lamp appearance of a 59-year-old female with pseudoexfoliation of the lens capsule. Pseudoexfoliative material. is visible at the pupil

margn.

special group as these patients often have a very irregular corneal endothelium with considerable pleomorphkm and p~lymegathism~~-” SO that the viability of the cornea for use as donor material in corneal grafting may be in question, at least for young patients, especially as the endothelial function has been shown to vary with the degree of polymegathism.’” A careful follow- up of these patients is desirable. Further, the presence of a posterior chamber intraocular lens (Case 6) may easily be overlooked although examination of the corneal endothelium will show that the cornea is unsuitable for use for grafting in many of these cases. It is important to always examine several areas of the corneal endothelium, especially in cornea guttata, as demonstrated by Cases 3 and 4.

Coexisting diseases such as pseudoexfoliation of the lens capsule may, however, not lower the count significantly (Case 7), although in many cs~fes endothelid changes are seen.” This empha- sises the importance of specular microscopy in all cases.

That age does not render a cornea unsuitable for grafting is shown by the 87-year-old man with a normal endothelium and a high cell count even after intraocular surgery some years before (Case 8), although overall a decreased countZo and increased mean cell area occurs with increasing age.19

That an ideal result is attainable if good material is used is shown by the grafted eye with a normal endothelium and high cell count following a triple procedure for a decompensated

Figure 19: Specular microscopy of the same eye as Figure 18 showing the normal corneal endothelium. Endothelial cell count 2750 cells/mm’ with a regular

mosaic. Bar = 100 pm.

Figure 17: Specular microscopy of the same eye as Fgwe 16. The endothelial cell wunt is 2700 cells/mm2

with a regular mosaic. Bar= 100 pm.

3 14 AUSTRALIAN AND NEW ZEALAND JOURNAL OF OPHTHALMOLOGY

Figure 20: Slit-lamp appearance of a 69-year-old female following a triple procedure for decompensated

Fuchs’ corneal dystrophy.

Figure 22: Slit-lamp appearance of the unoperated fellow eye with cornea guttata showing the normal

appearance of the cornea.

Figure 21: Specular microscopy of the same eye as Figure 20 showing the normal endothelium with an endothelial cell count of 3000 cells/mm’ and a regular

mosaic. Bar= 100 pm.

Fuchs’ dystrophy (Case 9). With careful quality control this should not be an occasional outcome but the usual result of corneal grafting.

ACKNOWLEDGEMENTS We wish to thank the Department of Medical Illustration of the Royal Victorian Eye and Ear Hospital, Mr Terry Young, Mr Andrew Newton and Mrs Brenda Hallam for their invaluable assistance. This work was carried out under Research Projects 20 and 92 of the Royal Victorian Eye and Ear Hospital.

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Figure 23: Specular microscopy of the same eye as Figure 22. There are numerous small guttae and an endothelial cell count of I225 cells/mm’ with mild pleomorphism and polymegathism. Bar = I00 pm.

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18. Forster RK, Fine M. Relation of donor age to success in penetrating keratoplasty. Arch Ophthalmol 1971; 85: 42-47.

19. Laing RA, Sandstrom MM, Berrospi AR, Leibowitz HM. Changes in the corneal endothelium as a function of age. Exp Eye Res 1976; 22: 587-594.

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23. Sweeney DF, Holden BA, Vannas A et al. The clinical significance of corneal endothelial polymegathism. Invest Ophthalmol Vis Sci 1985; 26 (suppl): 53.

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(Received 18 Aprii 1988)


the preoperative assessment of the corneal endothelium

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