臨床上進行眼科學檢查流程時，眼用局部麻醉劑被用來減輕操作時產生的疼痛及不舒適感已有多年，但從未被當作治療用途使用。近年來有人將嗎啡類藥物局部點眼使用並研究其對於角膜止痛之效果，結果顯示這類藥物可以提供局部的止痛而且不會延遲角膜傷口癒合。其中，以 nalbuphine 粉末加上液體配製成具有適當酸鹼值的 1% nalbuphine 溶液，曾被評估在點眼使用後對於犬及馬的角膜是否能產生止痛效果。本實驗目的是將商品化的 nalbuphine 注射液進行鹼化及稀釋，評估此藥對於白內障超音波乳化手術所造成的術後疼痛是否能提供良好的止痛效果。此外，其對於角膜敏感度的影響也在本實驗評估的項目之中。本實驗對象為 11 隻患有白內障並至中興大學獸醫教學醫院就診之犬隻。將 12 個接受白內障超音波乳化術的眼睛以隨機分組的方式分為 saline 組 (n= 6) 與 nalbuphine 組(n=6)，各組分別接受以 0.1 ml的 saline 或 nalbuphine 局部點眼。所有評估項目於術前及術後點藥前皆會先取得其
基本數值，再比較術前與術後及點藥前與點藥後的差異。於術後，角膜敏感度、眼瞼痙孿、角膜水腫、結膜充血及前房混濁程度、眨眼頻率及瞳孔大小皆在點藥前及點藥後的 15，30 及 60 分鐘後進行測量並記錄。於角膜敏感度部分，nalbuphine 組在術後第一及第二天於點藥前後皆出現顯著差異。兩組間的眼瞼痙孿程度在術後第一天並無顯著差異(p = 0.1)，而於術後第二天則出現顯著差異(p =0.001)。眨眼頻率同樣是在術後第二天於點藥前及點藥後，兩組間皆出現顯著差異。由研究所得的數據顯示出 nalbuphine 組在術後第二天，其眼瞼痙孿程度及眨眼頻率相較於 saline 組皆有顯著減少。目前的研究結果顯示，0.8% nalbuphine 局部點眼的 15, 30 及 60 分鐘後可以使角膜敏感度減低。其對於白內障乳化術造成的術後疼痛，也具有些微緩解的效果。

Topical ophthalmic anesthetics have been used for many years to prevent pain and discomfort during ophthalmic tests and procedures, but never for therapeutic purposes. Recently, data have been obtained which suggest that topical application of opioids may
also provide localized analgesia with no delay in corneal wound healing. 1% nalbuphine solution prepared by adding powder nalbuphine to aqueous solution with an appropriate
pH level has been used topically for evaluating the analgesic effect in dogs and horses. The aim of this study was to evaluate the effect of diluted and alkalized commercial nalbuphine injection on signs of postoperative pain and corneal sensitivity in dogs
undergoing phacoemulsification. Twelve eyes from eleven dogs undergoing phacoemulsification cataract surgery at veterinary medical teaching hospital, National Chung Hsing University were included in this study. The subjects were divided into two groups: saline group (n = 6) and nalbuphine group (n = 6). 0.1 ml saline or nalbuphine
solution was instilled in randomly selected eye. Baseline values of all assessments were measured in surgical eyes before and after phacoemulsification. Postoperatively, corneal touch threshold (CTT), the extent of blepharospasm, corneal edema, conjunctival hyperemia and flare, frequency of eyelid blink and pupil diameter for each eye were recorded before and at 15, 30 and 60 minutes following nalbuphine or saline administration. The significant differences in CTT were noted between values before and after nalbuphine treatment on day 1 to 2 after surgery. There was no significant difference in scores for blepharospasm between two groups before treatment on day 1 (p = 0.1), whereas a significant difference was noted on day 2, postoperatively (p = 0.001). The
significant differences in eye blink frequency between two groups were noted before and after treatment on day 2. According to the results, a significant reduction in blepharospasm and eye blink frequency was observed in the nalbuphine group on postoperative day 2. The present results of the study indicate that prepared 0.8% nalbuphine solution can decrease the corneal sensitivity at 15, 30 and 60 minutes after topical administration and it may has little effect on ocular pain relief after phacoemulsification.

Abstract: English version ············································· i
Abstract: Chinese version ············································· iii
List of figures ······················································ vi
List of tables ······················································· vii
1. Introduction······················································ 1
2. Literature review ·················································· 3
2.1. Neural basis of sensation in corneas································ 3
2.1.1. Corneal sensory nerve fibers and their functional characteristics······ 3
2.1.2. Measurement of corneal sensitivity····························· 5
2.1.3. Activities of corneal sensory fibers in injured and inflamed corneas ··· 5
2.1.4. Action of drugs on corneal sensory fibers························ 6
2.2. Topical ophthalmic anesthetics and analgesics························ 7
2.2.1. Topical anesthetics·········································· 7
2.2.2. Topical non-steroidal anti-inflammatory drugs (NSAIDs) ··········· 8
2.2.3. Topical opioids············································· 9
2.3. Phacoemulsification ············································ 11
2.3.1. Procedures of surgery involved cornea ·························· 11
2.3.2. Intraoperative and postoperative pain ··························· 12
2.3.3. Postoperative changes in corneal sensitivity······················ 14
3. Materials and methods·············································· 16
3.1. Animals and materials··········································· 16

3.2. Methods ····················································· 17
3.2.1. Pre-surgical and post-surgical evaluation ························ 17
3.2.2. Protocol of phacoemulsification ······························· 20
3.2.2.1. Pre-surgical treatment···································· 20
3.2.2.2. Surgical procedures······································ 20
3.2.2.3. Post-surgical treatment··································· 22
3.2.3. Study procedures··········································· 22
3.2.3.1. Preparation of 0.8% nalbuphine solution ····················· 22
3.2.3.2. Study design··········································· 24
3.3. Statistical analysis·············································· 24
4. Results·························································· 25
4.1. Baseline characteristics·········································· 25
4.2. Changes in cornea, conjunctiva and anterior chamber·················· 26
4.3. Corneal sensitivity ············································· 28
4.4. Blepharospasm ················································ 29
4.5. Eye blink frequency ············································ 33
4.6. Pupil size····················································· 34
4.7. Schirmer tear test ·············································· 36
5. Discussions ······················································ 38
References························································· 45

Acosta MC, Belmonte C, Gallar J, et al. Sensory experiences in humans and
single-unit activity in cats evoked by polymodal stimulation of the cornea. J Physiol
534.2: 511–525, 2001

Acosta MC, Berenguer-Ruiz L, Garcı´a-Ga´lvez A, et al. Changes in Mechanical,
Chemical, and Thermal Sensitivity of the Cornea after Topical Application of
Nonsteroidal Anti-inflammatory Drugs. IOVS 46: 282-286, 2005.

Acosta MC, Tan ME, Belmonte C, et al. Sensations Evoked by Selective Mechanical,
Chemical, and Thermal Stimulation of the Conjunctiva and Cornea. IOVS 42:
2063-2067, 2001.

Aquino S, van der Woerdt A, Eaton JS, et al. The effect of topical nalbuphine on
corneal sensitivity in normal canine eyes. Proc Am Coll Vet Ophthalmol 36:43, 2005.

Awan AH. Subjective Assessment of Pain Level during Phacoemulsification and Extra
Capsular Cataract Extraction with Intraocular Lens Implantation under Topical
Anesthesia. Pak J Ophthalmol 25: 161-164, 2009.

Barrett PM, Scagliotti RH, Merideth RE, Jackson PA, Alarcon FL. Absolute corneal
sensitivity and corneal trigeminal nerve anatomy in normal dogs. Prog Vet Comp
Ophthalmol 1: 245–254, 1991.

Bates BD, Mitchell K, Keller JM, et al. Prolonged analgesic response of cornea to
topical resiniferatoxin, a potent TRPV1 agonist. Pain 149: 522–528, 2010.

Bekendam PD, Narváez J, Agarwal M. Case of Corneal Melting Associated With the
Use of Topical Nepafenac. Cornea 26: 1002-1003, 2007.

Belmonte C, Acosta MC, Gallar J, et al. Neural basis of sensation in intact and injured
corneas. Exp Eye Res 78: 513–525, 2004.

Belmonte C, Gallar J, Pozo MA, et al. Excitation by irritant chemical substances of
sensory afferent units in the cats cornea. J Physiol 437: 709-725, 1991.

Belmonte C, Gallar J. Corneal nociceptors. In: Neurobiology of Nociceptors, ed.
Belmonte C. & Cervero F., Oxford University Press, New York, 146–183, 1996.

Belmonte C, Garcia-Hirschfeld J, Gallar J, et al. Neurobiology of Ocular Pain. Prog
Retin Eye Res 16: 117-156, 1997.

Belmonte C, Giraldez F. Responses of cat corneal sensory receptors to mechanical
and thermal stimulation. J Physiol 321: 355-368, 1981.

Bessou P, Perl ER. Response of cutaneous sensory units with unmyelinated fibers to
noxious stimuli. J Neurophysiol 32: 1025-1043, 1969.

Brooks DE, Clark CK, Lester GD. Cochet-Bonnet aesthesiometer-determined corneal
sensitivity in neonatal foals and adult horses. Vet Ophthalmol 3: 133-137, 2000.

Chuck RS, Quiros PA, Perez AC, et al. Corneal sensation after laser in situ
keratomileusis. J Cataract Refract Surg 26: 337–339, 2000.

Clark JS, Bentley E, Smith LJ, et al. Evaluation of topical nalbuphine or oral tramadol
as analgesics for corneal pain in dogs: a pilot study. Vet Ophthalmol 14: 1–7, 2011.

Colin J, Paquette B. Comparison of the analgesic efficacy and safety of nepafenac
ophthalmic suspension compared with diclofenac ophthalmic solution for ocular pain
and photophobia after excimer laser surgery: a phase II, randomized, double-masked
trial. Clin Ther 28:527-536, 2006.

ECRI. Scleral and Corneal Burns during Phacoemulsification. HD 25 :426-431, 1996.

Faktorovich EG, Basbaum AI. Effect of topical 0.5% morphine on postoperative pain
after photorefractive keratectomy. J Refract Surg 26: 934-941, 2010.

Gaynes BI, Fiscella R. Topical Nonsteroidal Anti-Inflammatory Drugs for Ophthalmic
Use: A Safety Review. Drug Saf 25:233-250, 2002.

Gelatt KN, Gelatt JP. Surgical procedures of the lens and cataracts. In: Small Animal
Ophthalmic Surgery: Practical Techniques for the Veterinarian.
Butterworth-Heinemann, Oxford, 286-334, 2001.

Grant RL, Acosta D. Comparative Toxicity of Tetracaine, Proparacaine and Cocaine
Evaluated with Primary Cultures of Rabbit Corneal Epithelial Cells. Exp Eye Res 58:
469-478, 1994.

Guidera AC, Luchs JI, Udell IJ, et al. Keratitis, ulceration, and perforation associated
with topical nonsteroidal anti-inflammatory drug. Ophthalmology 108: 936-944,
2001.

Han-Ling T. Sensitivity and neural organization of the cat cornea. Invest Ophthalmol
Vis Sci 30: 1075–1082, 1989.

Henkes HE, Waubke TN. Keratitis from abuse of corneal anaesthetics. Br J
Ophthalmol 62: 62-65, 1978.

Herring PI, Bobofchak AM, Landry PM, et al. Duration of effect and effect of
multiple doses of topical ophthalmic 0.5% proparacaine hydrochloride in clinically
normal dogs. AJVR 66:77-80, 2005.

John T. Corneal sensation after small incision, sutureless, one-handed
phacoemulsification. J Cataract Refract Surg 21: 425–428, 1995.

Jones M, Marfurt CF. Peptidergic innervation of the rat cornea. Exp Eye Res 66:
421–435, 1998.

Kecová H, Neâas A. Phacoemulsification and Intraocular Lens Implantation: Recent
Trends in Cataract Surgery. Acta Vet Brno 73: 85-92, 2004.

Khalifa YM, Mifflin MD. Keratitis and Corneal Melt With Ketorolac Tromethamine
After Conductive Keratoplasty. Cornea 30: 477-478, 2011.

Khanal S, Tomlinson A, Esakowitz L, et al. Changes in corneal sensitivity and tear
physiology after phacoemulsification. Ophthal Physiol Opt 28: 127–134, 2008.

Kohlhaas M, Stahlhut O, Tholuck J, et al. Development of corneal sensitivity after
phacoemulsification with scleral tunnel incision. Klin Monatsbl Augenheilkd 211:
32–36, 1997.

Larson WL. Electro-mechanical corneal aesthesiometer. Brit J Ophthal 54: 342-347,
1970.

Liu JC, Steinemann TL, McDonald MB, et al. Topical Bupivacaine and Proparacaine:
A Comparison of Toxicity, Onset of Action, and Duration of Action. Cornea 12:
228-232, 1993.

Lyne A. Corneal sensitivity after surgery. Trans Ophthalmol Soc UK 102: 302–305,
1982.

Maclver MB, Tanelian DL. Structural and functional specialization of A-delta and C
fiber free nerve endings innervating rabbit corneal epithelium. J Neurosci 13:
4511-4524, 1993.

Maggas DJ. Ocular pharmacology and therapeutics. In: Maggs DJ, Miller PE and Ofri
R, eds. Slatter’s fundamentals of veterinary ophthalmology. 4th ed. Saunders Elsevier, St. Louis, Mo., 33-61, 2008.

Marfurt CF, Ellis LC. Immunohistochemical localization of tyrosine hydroxylase in
corneal nerves. J Comp Neurol 336: 517–531, 1993.

Marfurt CF, Murphy CJ, Florczak JL, et al. Morphology and Neurochemistry of
Canine Corneal Innervation. Invest Ophthalmol Vis Sci 42: 2242-2251, 2001.

Mu¨ller LJ, Marfurt CF, Kruse F, et al. Corneal nerves: structure, contents and
function. Exp Eye Res 76: 521–542, 2003.

Murphy CJ, Marfurt CF, McDermott A, et al. Chronic corneal epithelial defects in
dogs: clinical features, innervation and effect of topical substance P, with and without
IGF-1. Invest Ophthalmol Vis Sci 42: 2252–2261, 2001.

Murphy PJ, Lawrenson JG, Patel S, Marshall J. Reliability of the Non-Contact
Corneal Aesthesiometer and its comparison with the Cochet-Bonnet aesthesiometer.
Ophthalmic Physiol Opt 18:532–539, 1998.

Murphy PJ, Patel S, Kong N, et al. Noninvasive Assessment of Corneal Sensitivity in
Young and Elderly Diabetic and Nondiabetic Subjects. IOVS 45: 1737-1742, 2004.

Nardi M, Lobo C, Bereczki A, et al. Analgesic and anti-infl ammatory effectiveness of
nepafenac 0.1% for cataract surgery. Clin Ophthalmol 1: 527–533, 2007.

Park SA, Park YW, Kim TH, et al. Evaluation of the analgesic effect of intracameral
lidocaine hydrochloride injection on intraoperative and postoperative pain in healthy
dogs undergoing phacoemulsification. AJVR 71:216-222, 2010.

Park SA, Park YW, Son WG, et al. Evaluation of the analgesic effect of intracameral
lidocaine hydrochloride injection on intraoperative and postoperative pain in healthy
dogs undergoing phacoemulsification. AJVR 71:216-222, 2010.

Perez-Santonja JJ, Sakla HF, Cardona C, et al. Corneal sensitivity after
photorefractive keratectomy and laser in situ keratomileusis for low
myopia. Am J Ophthalmol 127: 497–504, 1999.

Peyman GA, Rahimy MH, Fernandes ML, et al. Effects of morphine on corneal
sensitivity and epithelial wound healing: implications for topical ophthalmic analgesia.
Br J Ophthalmol 78:138-141, 1994.

Price MO, Price FW. Efficacy of topical ketorolac tromethamine 0.4% for control of
pain or discomfort associated with cataract surgery. Curr Med Res Opin 20:
2015-2019, 2004.

Rózsa AJ, Beuerman RW. Density and organization of free nerve endings in the
corneal epithelium of the rabbit. Pain 14: 105-120, 1982.

Shen Y, Tong JP, Li YM. Corneal relaxing incision combined with
phacoemulsification and IOL implantation. J Zhejiang Univ Sci 5: 985-988, 2004.

Spatola RA, Thangavelu M, Chanler HA. The effects of topical nalbuphine on canine
corneal cells in vitro (abstract). ACVO 40: 134, 2009.

Stewart R, Grosserode R, Cheetham JK, et al. Efficacy and Safety Profile of
Ketorolac 0.5% Ophthalmic Solution in the Prevention of Surgically Induced Miosis
During Cataract Surgery. Clin Ther 21: 723-732, 1999.

Stiles J, Honda NC, Krohne GS, et al. Effect of topical administration of 1%
morphine sulfate solution on signs of pain and corneal wound healing in dogs. AJVR
64: 813-818, 2003.

Tatsuhiko A, Tetsushi N, Mina M, et al. Three Cases of Corneal Melting After
Instillation of a New Nonsteroidal Anti-Inflammatory Drug. Cornea 25: 224-227,
2006.

Tutton MK, Cherry PM, Raj PS, et al. Efficacy and safety of topical diclofenac in
reducing ocular pain after excimer photorefractive keratectomy. J Cataract Refract
Surg 22: 536-41, 1996.

Tutton MK, Cherry PM, Raj PS. Efficacy and safety of topical diclofenac in reducing
ocular pain after excimer photorefractive keratectomy. J Cataract Refract Surg 22:
536-541, 1996.

Weinberger D, Ron Y, Lichter H, et al. Analgesic effect of topical sodium diclofenac
0.1% drops during retinal laser photocoagulation. Br J Ophthalmol 84:135-137, 2000.

Weinstock VM, Weinstock DJ, Weinstock SJ. Diclofenac and ketorolac in th treatment
of pain after photorefractive keratectomy. J Refract Surg 12:792-794, 1996.

Wenk HN, Nannenga MN, Honda CN, et al. Effect of morphine sulphate eye drops on
hyperalgesia in the rat cornea. Pain 105: 455–465, 2003.

Wotman LK, Utter EM. Effect of treatment with a topical ophthalmic preparation of
1% nalbuphine solution on corneal sensitivity in clinically normal horses. AJVR
71:223-228, 2010.

Zacny JP, Conley K, Marks S. Comparing the Subjective, Psychomotor and
Physiological Effects of Intravenous Nalbuphine and Morphine in Healthy Volunteers.
J Pharmacol Exp Ther 280:1159-1169, 1997

Zander E, Weddell G. Observations of the innervation of the cornea. J Anat 85: 68–99,
1951.

Zanini M, Savini G, Barboni P. Corneal melting associated with topical diclofenac use
after laser-assisted subepithelial keratectomy. J Cataract Refract Surg 32:1570-1572,
2006.

Zuazo A, Ibafiez J, Belmonte C. Sensory nerve responses elicited by experimental
ocular hypertension. Exp Eye Res 43: 759-769, 1986.