ACTA OPHTHALMOLOGICA VOL. 4 0 1962

From the Ophthalmological Department, University of Helsinki (Chief: Prof. Salme Vannas, M . D . )

and IV Medical Clinic, University of Helsingfors (Chief: Prof. 3. v. Bonsdorff, M. D.)

P'I'ERYGIUM AND ITS RELATION TO ARCUS SENILIS,

PINGUECULA AND OTHER SIMILAR CONDITIONS")

BY

Henrik Forsius and Aldur Eriksson

It is generally held that pterygium is a product of prolonged exposure to irritants encountered in the open air. Peristasis factors in combination with a non-sex-linked, simple dominant gene with low penetrance and unsteady expressiveness may result in pterygium. Degenerative changes obviously also have a role as a predisposing factor.

The communications published on the pathogenesis of pterygium indicate that there are divergen8 schools of thought. Alt , Kamel, Friede etc. consider pterygiuin to be a product of inflammation; Fuchs, Friedenwald, Duke-Elder, Hilgers, Elliot and others hold that it is a peripheral degeneration of the cornea. 'The etiology of pterygium is further connected with its specific site at the border of two kinds of epithelium.

Pterygium and pinguecula The commonest sign of degeneration considered to have a role in the genesis

of pterygium is pinguecula. The first workers to suggest that there is a cqn- nection between pterygium and pinguecula were Zehender (1869), Mannhardt and Fuchs. Pinguecula's significance for the etiology of pterygium was stressed also by d'ombrain, Sugar, Kamel, Kerkenezow and Hilgers, but Schoninger, Hubner and Friede saw no correlation between these limbus affections. Nor did Hilgers always encounter a pinguecula in fully developed pterygia. I t was pointed out by Fuchs (1892) that the pinguecula tissue may become absorbed in fully developed pterygia, of course, obscuring the causal connection. This view has been repeated by later workers in slightly different words. Anderson

Aided by a grant from Sigrid Jusklius Stiftelse, Helsingfors. ") Received May 31st 1962.

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interviewed ophthalmologists interested in pterygium and heard both views - that pinguecula has an etiologic importance and that it has not. Anderson himself holds that dry winds and dust are associated with early pingueculae. Elliot is of the opinion that pinguecula and pterygium are both conditions caused by damage resulting from solar radiation and drying of the inter- palpebral tear film. Chronic infection and allergic reaction have also been connected with both conditions.

Pinguecula can be seen biomicroscopically in all persons over 70 years of age (Hinnen). How small changes can be called pinguecula is, of course, a matter of opinion. Kerkenezow compared the incidence of inflamed pingue- culae (causing symptoms) and pterygia in men and women. He found that a greater percentage of men had pinguecula and pterygium ( 1 1 and 12.7 per cent, respectively) than women (8.4 and 6.4).

Several of the authors cited hold that the pinguecula frequency is high in districts with a high incidence of pterygium.

Genealogical studies have shown that pinguecula is hereditary (Voegeli, Huber, Vogt and his co-workers).

Pterygium and arcus senilis Arcus senilis has been mentioned in discussion of the cause of pterygium.

Attias stated that a pronounced pinguecula can cause the development of an arcus, often very marked, close by the affection. This phenomenon can also be caused by a tumour close to the limbus as was later observed by Teegler and Forsius (1954). A lucid zone is usually seen between the arcus and the limbal affection. If the affection penetrates into the cornea the arcus can be seen, with the lucid zone preserved, to follow the new limbus forming a concave arc (see Fig. 1 a).

Mulock-Houwer noted that pterygium originates nasally or temporally, that is in the places where the arcus senilis usually is most weak. Diponegro and

Fig. I a. Fig. I b. a. Arcus senilis in a case with tumour close to the corneal limbus. The arcus, with

the lucid zone preserved, follows the new limbus forming a concave arc. b. Pterygium in a person with marked arcus senilis. As in Fig. 1 a the arcus curves

in towards the centre of the cornea.

403 Acta Ophthalmol. 40, IV 28

Mulock-Nouwer thought that arcus acted as a barrier to the formation of pterygium. The same line of thought was advanced by Gibson: A pterygium with a tendency to occur is discouraged by the presence of a well-marked arcus senilis.

Two cases with arcus senilis where pterygium could be observed growing over the arcus senilis were reported by Hilgers: >>It may be possible that in some cases without a fully established arcus senilis in which only the opacity in the region of Descemet's membrane is present and not the opacity in Bowman's region, this partial arcus senilis may not be able to act as a barrier...

One explanation of the fact that pterygium recurs more easily in young persons i s that the arcus protects against pterygium (Diponegro and Mulock- Hoicwer and Gibson). Schoninger, on the other hand, held that degenerative limbal affections such as arcus senilis predisposed to pterygium.

Sex

SERIES .4ND METHOD

Age, years

No. c 20 20-39 40-59 60 -+

The authors collected 36 cases of pterygium from the Central Hospital, Uni- versity ol Helsinki, including 9 cases from a private ophthalmological surgery in Helsinki (Forsius). They were anlysed for vision and refraction, profession, eye diseases, arcus senilis, intensity of the pinguecula, degree of atrophy and colour of the iris, colour and degree of irritation of the conjunctiva, sclerosis of the: ocular fundus, etc.

Arcus senilis was classified as marked when the arcus opacity was seen throughout the superficial layers and through the parenchyma as a whole at least a t some site, weak when seen without a biomicroscope, and microscopic when disc ernible only biomicroscopically (Forsius 1954).

P i n g u e d a was classified as extremely pronounced ( 3 ) , moderately pro- nounced (2), hardly discernible (1) and absent (0). The degree was determined separately temporally and nasally in both eyes and the mean of these 4 values

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was calculated. The gradation was performed with the aid of a binocular magnifying glass (+ 5 D) and good light from the side.

The age distribution is given in Table 1. As the degree of the pinguecula differed in persons of different sex and

age and in different occupations (indoor or outdoor work), the pterygium patients with pinguecula were distributed according to sex, age and occupation. In the 33 cases of pterygium (20 men and 13 women) where pinguecula was investigated, 14 men and 6 women were outdoor workers.

RESULTS

Pterygium and fiinguecula. The average degree of the pinguecula was 2.0 in the 14 male outdoor workers. This value differs essentially from the mean for a normal material in an earlier investigation (Forsius & Eriksson, 1962). The lowest value, 1.0, was encountered in two probands in this group. The highest value, 2.75, was recorded for a general labourer of 65. The mean pinguecula value for 6 male indoor workers was 1.54 (range 1.0-2.5), for 6 female outdoor workers 1.72 (range 1.0-2.5). For 7 female indoor workers it was 1.50 (rangq 0-2.25).

The 1 1 persons with pterygium in both eyes were divided between the same age classes as the other pterygium carriers. Seven of them were men, 2 indoor workers; and 4 women, all indoor workers.

The degree of pinguecula in the unilateral pterygia was equally marked on the pterygium (1.85) as on the nasal side (1.87) of the healthy fellow eye. The pinguecula was considerably more developed both nasally (2.5) and laterally (1.83) in pterygia in both eyes than in unilateral pterygium (1.86 and 1.14 respectively).

Only one person, a male outdoor worker of 55, had pterygium laterally (in addition to nasal pterygium in the same eye). The pinguecula was hardly dis- cernible here (1.0 laterally and 2.0 nasally).

The pinguecula was more marked nasally than laterally in all but 2 of the cases studied. The average values were 1.38 temporally and 2.07 nasally.

Pterygia in subjects under 50 had a less developed pinguecula than in the other subjects in this series. The difference, however, was no greater than in a normal series.

A married woman of 7 7 in Helsinki had no pinguecula despite pterygium medially in her left eye.

Pinguecula was extremely pronounced in 1 1 patients in at least one of the 4 different sites, 6 of them only on the side of pterygium. Correlation between fiterygium and arcus senilis corneae. The degree of arcus senilis varies and corresponds on the average with that encountered in the same age classes without pterygium.

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Fig. 2 a. Fig. 2 c. Fig. 2 b. Sagittal section of the cornea and pterygium in an eye with marked arcus senilis. a. The ptcrygium has not affected the arcus senilis. b. Arcus senilis is absent in the part of the corneal parenchyma that lies nearest to

the pteiygium, which has thus either prevented the arcus from forming or resorbed the arcus tissue.

c. A case of weak arcus senilis i s an eye with pterygium. Arcus tissue is absent in the deep layers of the corneal parenchyma. In the other eye, with no pterygium, artus stnilis is seen both in the superficial and deep parenchymal layers.

In 5 ca~es with pterygium and strongly developed arcus senilis the arcus curved inwards towards the centre of the cornea (see Fig. 1 b) leaving a distinct lucid zone between itself and the pterygium tissue. The arcus in these cases was more pronounced at the apex of the pterygium than on the contra- lateral (temporal) side.

No displacement inwards of the arcus senilis was seen in 4 other cases of pterygium (Fig. 2 a). In one of these 4 cases the arcus was normally located and the arcus tissue appeared massive even in the superficial strata of the corned. A gentle inward curving of the arcus tissue was observed on the temporal 4de where a pronounced pinguecula was close to the limbus. The pterygium of this woman of 53 was prominent and inflamed (see photo/Fig. 3).

Another feature seen in 2 persons with pronounced and 2 with weak arcus was that the arcus was not in its normal place in the parenchyma but only in the deeper layers (Fig. 2 b). In another patient the arcus was absent in the pterygium and began only above and below the pterygium, first in the deeper layers. This was so although the degree of the arcus was such that there should have been an opacification even in the superficial parenchymal layers (Fig. 2 c). Thus a lucid zone was formed in depth in the corneal parenchyma lying under the pterygium. The course of the pterygium often seemed to be com- pletely un'iffected and, as far as could be seen, the tissue appeared to be mas- sive almost right up to the pterygium. Correlatioii between the pterygium and the iris and conjunctiva. The colour of the iri5 varied between No. 2 and 6 practically over the entire colour range. but in relation to the normal population there was perhaps a pre- dominance of the lighter colours according to the eye colour table ,Augen- farben-Tafel nach Rud. Martin und K. Sallera with 8 different shades of colour

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a.

b.

Fig. 3 a. Fig. 3 b. A marked arcus senilis in the left eye in a woman of 55 with nasal pterygium. Massive arcus tissue in the corneal parenchyma as in Fig. 2 a. Right eye of the same patient. Inward curving of the arcus is seen temporally towards the centre of the cornea with blood vessels of a pinguecula invading the conjunctiva corneae. The arcus senilis was of roughly the same degree 6 months after the pterygium operation, when the picture was taken, but it was broader and more diffusely demarcated.

In the 18 cases examined the iris was strongly atrophic in 7-2 of them were under 65 years old - and mildly atrophic in 4 cases; biomicroscopically, atrophy was absent in 7 cases.

The degree of conjunctival irritation was evaluated on the basis of the colour of the conjunctiva, secretion and swelling of the glands in the eyelids. No deviation was seen in this respect from the normal population.

Pterygium and other diseases. Four of the 36 persons examined had glaucoma simplex and 3 had glaucoma capsulare. Four had cataracta senilis, 2 a per- forating wound (not in the area of the pterygium), 2 strabismus and in one case each the diagnosis was ectropium palpebrae inferior, uveitis chronica Fuchs, xanthelasma, keratitis profunda and retinitis diabetica. Six patients had more or less pronounced fundal sclerosis. One also had synchysis scintil- lans. Three of the persons with pterygium had diabetes. Three had high blood pressure, 2 had had apoplexy, 2 lues and there were cases of gallstones, tumor medullae spinalis, myodegeneratio cordis and debility.

DISCUSSION

Pterygium is relatively rare in Finland among patients consulting an ophthal- mologist; the incidence is 0.6 per cent (Forsius et d.), Pinguecula, on the other hand, occurs in the majority of older persons, especially men, but the expres- siveness varies considerably.

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In a noi.mal series of 700 persons the degree of pinguecula averaged 0.5-0.7 for female indoor workers over 30; for women in rural districts (farmer’s wives etc.) it was 0.8-1.0. The pinguecula was more pronounced as a rule in men. The mean was 1.1-1.3 for men over 30 with an indoor occupation and 1.25-1.6 for men working outdoors (Forsius et aZ.).

Comparison of the degree of pinguecula in pterygium probands and normal persons shows that the pinguecula is usually much more pronounced in the former even when the degree of the pinguecula on the site of the pterygium is disregarded.

The positive correlation between pterygium and pinguecula is, however, not absolute. ‘To mention an example, a married urban woman of 77 who had pterygium had no pinguecula. Pinguecula is absent in c. 20 per cent of female pterygium carriers aged over 70 (Forsius et al. 1962).

Five outdoor and 6 indoor workers of the 21 male pterygium carriers studied had faint11 developed or normal pinguecula. One of the 7 female indoor wor- kers and 2 of the 6 female outdoor workers (of the 13 female pterygium carriers studied) had faintly developed pinguecula.

The variation shown by arcus senilis in pterygia can probably be accounted for by the order of occurrence of these affections. If pterygium forms before arcus the arcus naturally follows the new limbal line and curves inwards forming a concave arc at the apex of the pterygium.

The fact that a lucid zone often is seen not only around the apex of the pterygium but also in depth in the corneal parenchyma may depend partly on the absorption of the arcus tissue, partly on the circumstance that the pterygium-provoked flow of fluid via the cornea prevents the origination of arcus opacification.

The degree of the arcus senilis was normal for the age, and hence there was no con1 irmation of the assertion in the literature that arcus prevents ptery- gium from forming. Arcus senilis is often strongly developed in Finland compared with other countries (Forsius 1954).

There was a tendency in the present series towards mild inverse astigmatism.. Direct astigmatism caused by the pressure of the pterygium on the cornea is a common finding in the literature. The pterygia reviewed here were small and the inverse astigmatism was more of senile etiology.

The degiee of the atrophy of the iris was greater than in a normal series judged by the same criteria. The same was true of 19 pterygium carriers in a fisher population whose heredity has been reviewed in another work (Forsius et aZ.). They included 2 persons with pseudoexfoliation lentis. If both these series are combined, there are 5 cases of pseudoexfoliatio lentis among 55 pterygium c arriers. I t must be mentioned, however, that capsular glaucoma is common in Finland; but the incidence does not approach 10 pe; cent, not even in the oldest age groups.

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S U M M A R Y

Thirty six pterygium patients, 23 males and 13 females, were examined for different degenerative conditions.

The average degree of pinguecuIa was much more pronounced in pterygium carriers than in a normal series of 700 persons. Of 20 male pterygium carriers. 5 of the 14 outdoor workers and 5 of the 6 indoor workers had normal or faintly developed pinguecula. Two out of the 6 female outdoor workers had faint pinguecula. Compared with unilateral pterygia, the degree of pinguecula was much more marked both nasally and temporally in persons with pterygia in both eyes. The pinguecula was equally pronounced in both eyes in persons with unilateral pterygium. It was more pronounced laterally than nasally in 2 cases only.

Arcus senilis corneae varied in pterygium. The degree of arcus senilis in pterygium carriers was normal for the age. Five of the 9 cases with strongly developed arcus senilis showed an inward curving of the arcus towards the centre of the cornea with preservation of the lucid zone (Fig. 1 b). This phenomenon was not observed in 4 cases. Four pterygium carriers displayed no arcus tissue in the parenchyma immediately under the arcus senilis (Figs. 2 b and 2 c).

The colour of the iris was not different from that in a normal population. But the iris was strikingly frequently atrophic. The degree of conjunctival irritation and secretion was not different from normal. Four of the pterygium carriers had senile cataract and 3 had simple glaucoma. Six of the pterygium carriers had more or less marked fundal sclerosis. Three had diabetes mellitus.

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