Treatment of Severe Acute Bacterial Keratitis in Rabbits Using Continuous Topical Ocular Instillation with Norvancomycin

Figures & data

Table 1 Clinical Score Standard of Keratitis Infected with S. aureus

Score	0	1	2	3	4
Discharge	No	Small amount	Medium amount	Large amount	Upper and lower eyelid adhesion
Conjunctiva (hyperemia/edema)	No	Slight	Mild	Moderate	Severe
Hypopyon	No	<1/4 of anterior chamber	1/4-1/2	1/2-3/4	>3/4
Cornea (infiltration/edema)	No	Transparent cornea, slight edema, scattered punctuate infiltrates, clearly visible iris texture	Moderate corneal opacity, infiltration area up to 1/4–1/2 of the entire cornea, still visible iris texture	Severe corneal opacity, corneal infiltrates up to 1/2–3/4 of the entire cornea, faint iris texture	Infiltration area >3/4 of the entire cornea, gray white opacity, invisible iris and pupil; 5 points: Corneal perforation

Figure 1 The flowchart demonstrates allocation to three groups, follow-up and investigations carried out at each time point.

Abbreviations: SLP, slit-lamp photography; AS-OCT, anterior segment optic coherence tomography; CTOIDD, continuous topical ocular instillation drug delivery; NVCM, norvancomycin.

Figure 2 The ring part of the CTOIDD system model was fixed on the conjunctiva of a rabbit eye.

Abbreviation: CTOIDD, continuous topical ocular instillation drug delivery.

Table 2 Clinical Scores in Three Groups

Parameters	Days	CTOIDD-Saline	CTOIDD-NVCM	Eye Drop-NVCM
Discharge	0	4 (3.6, 4)	4 (4, 4)	4 (3, 4)
Conjunctiva	0	4 (3.6, 4)	4 (3, 4)	3 (3, 4)
Cornea	0	4 (3.6, 4)	3 (3, 4)	4 (4, 4)
Hypopyon	0	3 (3, 3)	3 (1.5, 3.5)	3 (3, 4)
Total	0	14.75 (14, 15)	13 (12, 15)	14 (13, 15)
Discharge	4	3 (3, 3.75)	2 (1.75, 2)	2.5 (2, 3)
Conjunctiva	4	3 (3, 3.75)	2 (2, 3)	2.5 (2, 3)
Cornea	4	4 (3.63, 4.75)	3 (2, 3)	4 (3, 4)
Hypopyon	4	4 (3.25, 4)	2 (1, 3)	3 (3, 4)
Total	4	14.25 (13, 15)	8 (7, 11)	11. 5 (10.5, 13.5)
Discharge	8	2.5 (2, 3)	0 (0, 0)	1 (1, 1.75)
Conjunctiva	8	2.5 (2, 3)	1 (1, 1)	2 (2, 2)
Cornea	8	5 (3.38, 5)	2 (2, 2)	3 (3, 4.75)
Hypopyon	8	3 (3, 3)	1 (0.88, 1)	2 (2, 2)
Total	8	12.75 (11.38, 13.25)	4 (3, 4.25)	8 (8, 10.5)

Figure 3 Representative slit-lamp pictures of the CTOIDD-NVCM group (A–D), Eye drop group (E–H), CTOIDD-saline group (I–L). Pictures were taken on days one (A, E, I), two (B, F, J), four (C, G) and eight (D, H, L). Eyes in the CTOIDD-saline group presented a remarkable corneal edema and infiltration, conjunctival hyperemia and hypopyon. A typical corneal perforation with hyperemic iris incarceration on day six was observed in the CTOIDD-saline group (K). The eyes on day eight in the CTOIDD-NVCM and eye drop groups appeared less inflamed.

Figure 4 Clinical inflammation score changes in three groups (n=13 in CTOIDD-NVCM, n=11 in eye drop-NVCM, n=8 in CTOIDD-saline group on days one, two; n=10 in CTOIDD-NVCM group, n=8 in eye drop-NVCM group, n=6 in CTOIDD-saline group on days four, six, eight). Values are given as the median (IQR).

Figure 5 Comparison of inflammation scores in different days among the three groups. Kruskal–Wallis test was used to compare the difference with a posthoc test. Values are given as the median (IQR), *p<0.05, **p<0.01.

Figure 6 Representative pictures of AS-OCT examination in cornea. Cornea in healthy rabbit (A). Corneas in CTOIDD-NVCM group (B), eye drop group (C) and CTOIDD-saline group (D) on day eight, respectively.

Figure 7 Comparison of bacteria count in the three groups. One-way analysis of variance was used to compare the difference with a post hoc test. Values are given as mean ±SD, *p<0.05, **p<0.01.

Figure 8 Representative pictures of histopathological section images of cornea (A–E), iris (F–I) and ciliary body (J–M) in healthy rabbits and three groups on day eight. Healthy cornea (A), cornea in CTOIDD-NVCM group (B), eye drop group (C, E), CTOIDD-saline group (D). Healthy iris (F), iris in CTOIDD-NVCM group (G), eye drop group (H), CTOIDD-saline group (I). Healthy ciliary body (J), ciliary body in CTOIDD-NVCM group (K), eye drop group (L), CTOIDD-saline group (M). (A–C) 20× magnification, scale bar 50 μm; (D, E) 10× magnification, scale bar 100 μm; (F–M) 20× magnification, scale bar 50 μm, H&E stain.

Table 3 Pathological Scores of Cornea, Iris and Ciliary Body in Three Groups

Tissue	CTOIDD-Saline	CTOIDD-NVCM	Eye Drop-NVCM
Cornea	4 (4, 4)	2 (1.5, 2.5)	3.5 (3, 4)
Iris	4 (3, 4)	2 (1, 2.5)	2.5 (2, 3)
Ciliary body	3 (3, 3)	2 (1, 2)	2 (1.25, 2.75)

Figure 9 Comparison of pathology infiltration inflammation scores in three groups. Kruskal–Wallis test was used to compare the difference with a post hoc test. Values are given as the median (IQR), *p<0.05.