Ocular Complications Post-Dental Procedure

Prasannasai K, M. Optom

Department of Binocular Vision, Sankara Nethralaya, Chennai, India

 

Introduction

Local anaesthetics are vital in dentistry, with intraoral local anaesthesia being a common procedure. ^(1,2) Patients may experience typical ophthalmologic complications following either a posterior superior alveolar injection or an inferior alveolar injection during intraoral local anaesthesia. ⁽³⁾

These complications usually appear shortly after and often resolve as the anaesthesia wears off. They are commonly caused by the anaesthetic solution reaching the orbit or neighbouring structures. ⁽⁴⁾

Pathophysiology

In Fig 1, we observe the movement of local anaesthetic after an injection into the inferior alveolar nerve. If the anaesthetic accidentally enters the wrong artery, it can flow backward. This backward flow might help the anaesthetic move into the lacrimal artery, consequently dispersing into the ophthalmic artery through the anastomosis, potentially impacting the muscles of the eye. ⁽⁵⁾

 Figure 1: Illustrating movement of local anaesthetic after an injection into the inferior
alveolar nerve
[Picture courtesy: https://pocketdentistry.com/wp-content/uploads/2016/10/gr2-256.jpg]

Complications

Oculomotor nerve paralysis

The short ciliary nerves, originating from the ciliary ganglion, play a crucial role in ocular function. Their proximity to the optic nerve and the lateral rectus muscle renders them susceptible to the effects of anaesthesia. Paralysis of the Cranial Nerve III (oculomotor) can result from the anaesthetic’s impact on these nerves. ⁽⁶⁾

Incomplete Oculomotor nerve paralysis may cause strabismus due to internal rectus muscle spasms, difficulty focusing on near objects due to ciliary muscle spasms, or pupil constriction due to irritation of the pupil sphincter.

Complete paralysis of the Oculomotor nerve results in drooping eyelids, outward eye deviation, pupil dilation, and loss of focus adjustment, attributed to the paralysis of the pupil constrictor, ciliary muscle, and inner rectus muscle. ⁽⁷⁾

Amaurosis and Diplopia

Blaxter and Britten et al ⁽⁸⁾ reported cases of temporary vision loss and double vision, suggesting that an injection into the inferior alveolar artery led to the anaesthetic travelling through several arteries, including the internal maxillary, middle meningeal, and eventually reaching the lacrimal and ophthalmic arteries contributes to the visual disturbances.

In 1955, Pazmanyi et al ⁽⁹⁾ suggested that one case displayed transient amaurosis, ocular paresis, and exophthalmos due to vein irritation during injection, while another showed signs of central retinal artery occlusion caused by temporary reflex Angio spasm.

Pseudo Myopia

After recovering from general anaesthesia, the patient reported a blurred vision in both eyes, with no history of spectacle use. A comprehensive ophthalmic examination revealed unaided distant visual acuity of 20/1,000 bilaterally. Refraction confirmed a myopic shift, accepted as -3.00 DS (20/20 vision) in both eyes. Motor, anterior, and posterior segment parameters were normal. Cycloplegic refraction revealed a hyperopic shift.

The decision was made to monitor without intervention. Two days later, the patient reported no visual discomfort. It was believed that the pseudo myopia was induced by a spasm of the ciliary muscle.

Furthermore, it was suggested that lidocaine drug toxicity, causing circumoral numbness, tongue paraesthesia, and dizziness, was the cause of the spasm. ⁽¹⁰⁾

Conclusion

Healthcare providers must remain vigilant regarding ocular complications arising from dental injections. Dentists should prioritise precise techniques by comprehending these conditions. ⁽⁵⁾ Prompt diagnosis and reassurance help calm patients. Caution should be exercised against engaging in risky activities if vision is impaired until the effects of local anaesthesia wear off. ⁽¹¹⁾

 

References

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