Experience in Clinical Examination of Corneal Sensitivity: Corneal Sensitivity and the Naso-Lacrimal Reflex after Retrobulbar Anaesthesia

Comparison of peribulbar and retrobulbar regional anesthesia with bupivacaine in cats

“…In humans, tear production is decreased after RBA because the lacrimal nerve (small branch of the ophthalmic nerve) is blocked. 48 Although tear production was not recorded after injections in the present study, it returned to reference limits by 24 hours and did not differ from baseline values. Assuming that cats receiving RBA or PBA are less likely to reflexively blink and produce tears, it will make them more prone to corneal desiccation and potentially ulceration.…”

“…28 In a different study, 48 retrobulbar administration of 1 mL of 1% or 2% lidocaine to a person resulted in maximal reduction in corneal sensitivity at 5 minutes, and the duration of maximal effect was 40 minutes with 1% lidocaine (without epinephrine) and 120 minutes with 2% lidocaine in combination with epinephrine. In the present study, the median duration of maximal corneal anesthesia after PBA and intraconal RBA was approximately 3 hours; however, detectable corneal anesthesia lasted longer for both treatments.…”

“…The longer duration of effect for both techniques on pupil dilation and response to light in comparison to the duration of effect for sensation and other reflexes is also described in humans after retrobulbar injection of lidocaine. 48 This may be a result of the organization of parasympathetic fibers, which are concentrated around the oculomotor nerve and makes them particularly vulnerable to injury 33 or absorption of anesthetics. It may also be related to the increased sensitivity of autonomic fibers to anesthetics, compared with the sensitivity of sensory fibers.…”

Corneal Sensation After Overnight Orthokeratology

“…4 It is well known that contact lens wear causes loss of corneal sensation regardless of the lens material and wearing modality. [5][6][7][8][9] Clinicians have observed that contact lens wear can increase the corneal touch threshold to values that are so high that some patients do not experience any pain or discomfort even if the cornea is abraded. 10 In addition, several reports have suggested that the loss of corneal sensation resulting from wearing contact lenses increases the risk of infection.…”

The Interblink Interval I: The Relationship between Sensation Intensity and Tear Film Disruption

“…8,[21][22][23][24] At present, methods of assessing the sensations arising from the ocular surface representing the experience of ocular discomfort are limited. 25,26 Recently, ocular surface drying occurring during forced eye opening has been used to elicit acute discomfort in an attempt to understand corneal sensations in provoked dry eye. [27][28][29] We used this as a point of departure to characterize the dynamics of tear film drying and describe the nature of the associated changing sensations.…”