Study to Evaluate Safety, Tolerability and Pharmacokinetics of rhNGF Eye Drops in Healthy Volunteers

Inclusion Criteria: * Male or female subjects, aged between 18 and 60 years, inclusive. * Subject has to be able to communicate well with the investigator, understands and complies with the requirements of the study, and understands and signs the written volunteer informed consent form. * Subject's systemic and ocular medical history must be considered normal in the opinion of the investigator at the Screening and Baseline visits. * Best corrected distance visual acuity (BCDVA) score ≤ 0.00 LogMAR (≥83 ETDRS letters, 20/20 Snellen or 1.0 decimal fraction) in each eye at the Screening and Baseline visits. * Normal anterior segment on external and slit lamp examination in both eyes at the Screening and Baseline visits. * Normal posterior segment on fundus ophthalmoscopic examination in both eyes at the Screening and Baseline visits. * Subject must be considered in good systemic health in the opinion of the investigator at the Screening and Baseline visits, as determined by: 1. Subject's body mass index is between 18.5 and 30.4 kg/m2 inclusive 2. A pre-study physical examination with no clinically significant abnormalities. 3. Vital signs within clinically acceptable ranges for the purposes of the study (sitting systolic blood pressure \[BP\] ≥ 90 mmHg and ≤ 150 mmHg; diastolic BP ≥ 50 mmHg and ≤ 95 mmHg; heart rate (pulse rate) ≥ 40 and ≤ 100 beats per minute; oral body temperature ≥ 35.5°C and ≤ 37.5°C). 4. An ECG with no clinically significant abnormalities, in the opinion of the Investigator. 5. Pre-study clinical laboratory findings within normal range or not deemed clinically significant in the opinion of the investigator if outside of the normal range * Female subjects will be: * either post menopausal where post menopause is defined as the period following peri-menopause, i.e. postmenopausal after 12 months without a menstrual period and with a serum FSH value within the reference range for postmenopausal females at Screening * or permanently sterilised (e.g. tubal occlusion, hysterectomy, bilateral salpingectomy) * or be using 2 different forms of highly effective contraception throughout the study. Male subjects with female partners of child-bearing potential must use 2 different forms of highly effective contraception throughout the study and for a further 3 months after the follow-up visit and all male subjects must be willing to avoid donating sperm during this time. Exclusion Criteria: * Subject has had a clinically significant illness in the 6 weeks before screening in the opinion of the investigator. * Subject is not suitable to participate in the study in the opinion of the investigator * Subject has participated in any clinical study with an investigational drug/device within 3 months prior to the first day of dosing. * Subject has had a serious adverse reaction or significant hypersensitivity to any drug or chemically related compounds or has a clinically significant allergy to drugs, foods or other materials (in the opinion of the investigator). * Administration of any topical ocular (prescription or over the counter including artificial tears) or systemic medication including herbal product or fish oil preparations within 14 days before the first dose of study drug. Vitamins and mineral supplements not containing other substances are allowed until 96 hours before each dose if considered by the Investigator unlikely to interfere with the study results. Paracetamol at doses of at most 2 grams per day and ibuprofen at doses of at most 1200 mg per day for no more than 3 consecutive days or 6 non-consecutive days are allowed. Oral, injectable and implantable hormonal contraceptives are allowed without restrictions for female subjects. Longer exclusion periods apply for: 1. amiodarone and hydroxychloroquine (210 days), 2. monoclonal antibodies/ immunoglobulins/ other therapeutic proteins (120 days) 3. Experimental drugs with a half life known to the Study Unit: Five half lives plus 2 weeks 4. Experimental drugs with a half life unknown to the Study Unit: 120 days 5. chloroquine and flunarizine (100 days) 6. fluoxetine (75 days), 7. benzodiazepines different from midazolam, lorazepam and triazolam, chlorpromazine, mephenytoin, nortryptyline, phenobarbital, primidone, carbamazepine, phenytoin and phenprocoumon (35 days). * Subject has a significant history of drug/solvent abuse (within the last 2 years) or a positive drugs of abuse test at any time during the study. * Subject has a history of alcohol abuse (within the last 2 years) or currently drinks in excess of 28 units per week or has a positive alcohol breath test at any time during the study. * Subject is a smoker or has smoked in the 6 months prior to dosing. * Subject who has a positive human immunodeficiency virus (HIV) screen, hepatitis B screen or hepatitis C screen. * Subject has donated blood or blood products (e.g., plasma or platelets) within the 3 months prior to screening. * Subject has a partner who will be pregnant or breastfeeding during the study * Pregnant or breastfeeding female or those with a positive pregnancy test or who will not use a medically acceptable contraceptive method from selection and during the study * Subject having used any glucocorticosteroid by any route in the last 30 days whichever the route of administration, or any medication by ocular or nasal administration route from 30 days before screening. * Subjects currently diagnosed with any active ocular disease, even if mild, other than refractive error. * Subject with history of ocular surgery, including laser refractive surgery * Subject using a contact lens within 7 days prior administration of the first dose * Intraocular pressure (IOP) \>= 22 mmHg in either eye * Presence of any corneal opacity or corneal fluorescein staining \>0.5 grade using the modified Oxford scale * Schirmer's test without anesthesia \<= 9 mm/5 minutes * Tear film break up time \< 8 seconds