7.3  Clinical Examination of the Evolution of Chemical Eye Burns

applanation tonometer dangerous (risk of infection). It can now be done with lower risks of infection thanks to the use of an air-puff tonometer. In general, the ocular pressure is normal in the initial step.

7.2.4.3  Extraocular Signs

Most of the times, chemical eye burns are due to projections of chemicals to the face. It is important that the initial clinical analysis mentions the associated clinical signs, as far as the circumstances of the chemical burn often give them a medicolegal interest. These signs may be:

•Palpebral burns

•Face burns, the depth of which is to be estimated as first, second, or third degree. As these hurts are caused by liquid substances, in general, the burns are a little deep but really extended.

•Burns of the lacrymal system. They are uneasy to evaluate, however looking for a stenosis of the lacrymal point or canaliculi is essential. Concerning serious chemical eye burns, a systematic wash of the lacrymal system also enables to check its permeability.

•Burns of the nose mucous membrane, because of the chemical passing through the lacrymal system. It is necessary to do a nasal examination no later than the next day after the accident.

•Burns of the lips and mouth mucous membrane

7.3  Clinical Examination of the

Evolution of Chemical Eye Burns

There are two types of evolution.

7.3.1  Benign Ocular Burns

Benign ocular burns are grade 1 and grade 2 ocular burns. They evolve toward healing within 10 days or so. In this case, the epithelium of the cornea centripetally and gradually grows back. Treatments aim to prevent infectious complications and to support cicatrization.

7.3.2  Serious Ocular Burns

Serious ocular burns are grade 3 and grade 4 ocular burns. After primary alteration of the ocular biological tissues by the chemical, some biological reactions of cicatrization develop. As in any cicatrization, there are two phases: the detersion phase to eliminate the altered tissues and the repairing phase. Serious eye burns modify these two phases: they increase the ability of detersion and reduce the ability of reparation. Such a cicatrization then takes several weeks or months until consolidation of the lesions.

7.3.2.1  Complications on the Ocular Surface

Corneal Nonhealing

The absence of corneal cicatrization is illustrated by a recurrent ulcer of the cornea that will first reduce then form again and never heal (Fig. 7.12).

At such a step and every 48 h, there must be a thorough clinical examination of the corneal edema, because it is certainly a cause of the noncicatrization of the cornea. A good illustration of this phenomenon is the image of a roof collapsing because it is supported by a too weak structure. The epithelial

Fig. 7.12  Recurrent ulcer of the cornea after ocular burn by alkali (12.8% ammonia, pH = 11.5)

cells and particularly their basement membrane cannot be supported by a corneal stroma with edema. This clinical notion has a therapeutic interest: the use of anti-inflammatory and corticoid drugs to reduce and eliminate the edema. But these drugs have an inhibitive effect on the back growth of the epithelium, so they must be stopped as soon as the edema reduces, whereas the prescription of medicines facilitating the epithelialization must be increased. On the other hand, the stromal edema is not the only cause of the development of a marginal ulcer. The lack of limbal stem cells is also a primordial element of the evolution of this pathology. The evaluation of the remaining capital of the burnt eye is indirect and rough, and based on the observations of the initial examination. At this stage, while considering the rest of the ocular state, an autograft of limbus or a graft of amniotic membrane can be proposed.

The spontaneous evolution of this type of ulcer is dramatic and within a few weeks results in the conjunctival covering. This phenomena begins in the zone where limbal stem cells are the most insufficient, that is, as a general rule, in the inferior part. It gradually develops over the entire corneal surface and finally results in a complete conjunctiva that is completely covered and a loss of visual function of the damaged eye (Figs. 7.13 and 7.14).

The noncicatrization of the ulcer may also result in a spontaneous puncture of the cornea (Fig. 7.15).

Fig. 7.14  Old conjunctival covering due to eye burn. The patient perceives the light

Fig. 7.13  Beginning of a conjunctival covering after eye burn by alkali (12.8% ammonia, pH = 11.5)

Fig. 7.15  Spontaneous puncture of the cornea after eye burn by alkali (12.8% ammonia, pH = 11.5) with numerous symblepharons completely preventing the opening of the eyelids

Other Complications on the Ocular Surface

There might be other complications on the ocular surface like:

•Abscess of the cornea, which must be systematically prevented by checking the antitetanic vaccination and the prescription of local therapies by antibiotics.

•Symblepharons, which must also be systematically prevented by the installation of a symblepharon