Top-Line Results from theDry Eye Disease Chamber Crossover Trial of Reproxalap

Top-Line Results from theDry Eye Disease Chamber Crossover Trial of Reproxalap July 12, 2022 NASDAQ:

ALDX Aldeyra Therapeutics, Inc. 2022

2 This presentation and various remarks which may be made during this presentation contain

forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and Section 21E of the Securities Exchange Act of 1934, as amended, including statements regarding Aldeyra's possible or assumed future

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clinical trials may not be predictive of future results. As a result of the COVID-19 pandemic, clinical site availability, staffing, and patient recruitment have been negatively affected and the timelines to complete Aldeyra's clinical trials

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3 The ocular redness primary endpoint was achieved (P=0.0004). The Schirmer test primary endpoint was

achieved (P=0.0005). The multiplicity-controlled secondary endpoint of Schirmer test 10mm responder analysis was achieved (P=0.0361). Secondary endpoints for each assessed symptom (dryness, discomfort, grittiness, burning, stinging, and

itching) were achieved. All endpoints were assessed over approximately a 24-hour period of dosing, suggesting rapid activity of reproxalap. The crossover trial design appeared to reduce the high degree of variability characteristic of dry

eye disease clinical trials, at least for a drug with a potentially rapid mechanism of action. Topical ocular reproxalap is an investigational new drug candidate that has been studied in more than 1,800 patients with no observed safety

concerns; mild and transient instillation site discomfort is the most commonly reported adverse event in clinical trials. The Dry Eye Disease Crossover Trial Achieved Success for Three Dry Eye Disease Sign Endpoints and Six Secondary Symptom

4 Aldeyra Intends to Submit Symptom and Three Sign Endpoints to Support Dry Eye Disease NDA

Efficacy Requirements NDA submission requirements depend, in part, on clinical safety results and regulatory feedback. Topical ocular reproxalap is an investigational new drug candidate that has been studied in more than 1,800 patients

with no observed safety concerns; mild and transient instillation site discomfort is the most commonly reported adverse event in clinical trials. Based on previously announced clinical trials, the dry eye disease New Drug Application (NDA)

package for 0.25% reproxalap ophthalmic solution is expected to include two clinical trials for each of the following endpoints: Symptoms (ocular dryness symptom score) over 12 weeks, Ocular redness in a dry eye chamber, Schirmer test

following a single day of dosing, and Schirmer test 10mm responder analysis following a single day of dosing.

5 The Crossover Trial Represents a Unique Clinical Paradigm in Dry Eye Disease and Was Designed to

Serve as a Pivotal Trial NDA submission requirements depend, in part, on clinical safety results and regulatory feedback. Topical ocular reproxalap is an investigational new drug candidate that has been studied in more than 1,800 patients

with no observed safety concerns; mild and transient instillation site discomfort is the most commonly reported adverse event in clinical trials. The dry eye disease crossover trial was designed to eliminate inter-patient variability by

testing all interventions on each patient. To our knowledge, an adequate and well-controlled crossover trial has not been previously performed with an investigational drug candidate in dry eye disease patients. The dry eye disease

crossover clinical trial was intended to support the objective sign results from previously completed clinical trials. Because the crossover trial was designed to be adequate and well-controlled, and because the endpoints were

multiplicity-controlled, the trial was intended to be submitted as pivotal, assuming success, for one or more of the following objective sign endpoints: ocular redness, Schirmer test, and 10mm Schirmer test responder analysis.

Design Randomized, double-masked, crossover, vehicle-controlled, single-center Dosing 0.25%

reproxalap or vehicle, two-week washout Day 1: four doses Day 2: one dose before 90-minute dry eye chamber, one dose 45 minutes after chamber entry Size 63 patients Primary Endpoints Schirmer test on Day 1 (pre/post fourth

dose) Ocular redness in dry eye disease chamber Secondary Endpoints Schirmer test 10mm responder analysis Dry eye disease symptoms The Hochberg procedure was used to control for multiplicity. Unused alpha from the Hochberg

procedure was passed to a fixed sequence of secondaries, the first of which was the Schirmer responder analysis. Topical ocular reproxalap is an investigational new drug candidate that has been studied in more than 1,800 patients with no

observed safety concerns; mild and transient instillation site discomfort is the most commonly reported adverse event in clinical trials. Treatment Visits Each treatment visit represents Day 1 (pre-chamber) and Day 2 (chamber)

visits. Randomization 0.25% Reproxalap (n=32) Vehicle (n=~30) 0.25% Reproxalap Vehicle (n=31) Vehicle 2 week washout 6 The Crossover Trial Was Designed to Serve as a Pivotal Trial in Support of NDA Submission for Dry Eye Disease

7 P values derived from mixed effect model of repeated measures of change from baseline. Source: Dry

eye disease crossover clinical trial results on file. Topical ocular reproxalap is an investigational new drug candidate that has been studied in more than 1,800 patients with no observed safety concerns; mild and transient instillation site

discomfort is the most commonly reported adverse event in clinical trials. In the Dry Eye Disease Crossover Trial, Both Primary Endpoints Were Statistically Significant in Favor of Reproxalap over Vehicle Ocular Redness (Lower scores

favor reproxalap.) Tear Production (Higher scores favor reproxalap.)

8 *P < 0.05. SEM = standard error of the mean. mm = millimeter. Source: Dry eye disease crossover

clinical trial results on file. Topical ocular reproxalap is an investigational new drug candidate that has been studied in more than 1,800 patients with no observed safety concerns; mild and transient instillation site discomfort is the most

commonly reported adverse event in clinical trials. In the Dry Eye Disease Crossover Trial, Within-Patient Clinical Relevance Assessments Demonstrated Reproxalap Superiority Tear Production Ocular Redness

9 Reproxalap Vehicle 10 mm tear production post-Dose #4 on Day 1 48% 41% Odds ratio (95%

confidence interval) 1.551 (1.029, 2.338) P value versus vehicle 0.0361 Generalized estimating equation analysis of Schirmer test score 10mm pre- and post-Dose #4 on Day 1. Source: Dry eye disease crossover clinical trial results on

file. Topical ocular reproxalap is an investigational new drug candidate that has been studied in more than 1,800 patients with no observed safety concerns; mild and transient instillation site discomfort is the most commonly reported adverse

event in clinical trials. In the Dry Eye Disease Crossover Trial, the Multiplicity-Controlled Schirmer Test 10mm Responder Secondary Endpoint Was Achieved Schirmer Test Responder Analysis

10 P values derived from mixed effect model of repeated measures of change from baseline. Source: Dry

eye disease crossover clinical trial results on file. Topical ocular reproxalap is an investigational new drug candidate that has been studied in more than 1,800 patients with no observed safety concerns; mild and transient instillation site

discomfort is the most commonly reported adverse event in clinical trials. In the Dry Eye Disease Crossover Trial, Secondary Endpoints for All Assessed Symptoms Were

Achieved Dryness Discomfort Grittiness Stinging Burning Itching (collected pre/post chamber only)

11 The results suggest that a crossover design may reduce the high degree of variability

characteristic of dry eye disease clinical trials. The primary endpoints of ocular redness and Schirmer test were achieved. The Schirmer test 10mm responder analysis, which was also achieved, correlates with symptomatic improvement ,

consistent with the achievement of secondary endpoints for each of the assessed symptoms (dryness, discomfort, grittiness, stinging, burning, and itching). Consistent with prior trials, no clinically significant safety signals were

observed. A pre-NDA (New Drug Application) meeting has been scheduled for third quarter of 2022. Clinical data submitted to the NDA is expected to encompass acute (single-day dosing, dry eye chamber) and chronic (12-week) assessments, as

well as parallel-group and crossover clinical designs, offering what is expected to be unparalleled analysis of rapid and sustained activity across a combination of challenge and field-based assessments. Schiffman RM, Christianson MD,

Jacobsen G, Hirsch JD, Reis BL. Reliability and validity of the Ocular Surface Disease Index. Arch Ophthalmol. 2000;118(5):615-21. NDA submission requirements depend, in part, on clinical safety results and regulatory feedback. The NDA

submission is expected to include a combination of prespecified, post-hoc, primary, secondary, multiplicity-controlled, and nominal p-value endpoints. Topical ocular reproxalap is an investigational new drug candidate that has been studied in

more than 1,800 patients with no observed safety concerns; mild and transient instillation site discomfort is the most commonly reported adverse event in clinical trials. The Dry Eye Disease Crossover Trial Met Each of the Sign Endpoints

Intended to be Submitted to Support a Potential NDA

12 Reproxalap May Have the Potential to Address Significant Unmet Needs in Dry Eye Disease Holland

EJ, Cavanagh B, Machatha ST, et al. The Novel RASP Modulator Reproxalap Rapidly Improves Signs and Symptoms of Dry Eye Disease: The TRANQUILITY Run-In Cohort. Paper session presented at: Ocular Surface Disease III. ASCRS;2022 Apr 23;

Washington, D.C. Cavanagh B, Gomes PJ, Starr CE, et al. Ophthalmol Ther. 2022;11(4):1449-61. Clark D, Karpecki P, Salapatek AM, et al. Clin Ophthalmol. 2022;16:15-23. McMullin D, Clark D, Cavanagh B, et al. Clin Ophthalmol.

2021;15:3889-3900. Clark D, Sheppard J, Brady TC. J Ocul Pharmacol Ther. 2021;37(4):193-99. Clark D, Cavanagh B, Shields AL, et al. Am J Ophthalmol. 2021;230:60-7. Clark D, Tauber J, Sheppard J, Brady TC. Early Onset and Broad Activity of

Reproxalap in a Randomized, Double-Masked, Vehicle-Controlled Phase 2b Trial in Dry Eye Disease. Am J Ophthalmol. 2021 Jun;226:22-31. ClearView analysis of market research conducted Q4 2021 - Q1 2022. *White DE, Zhao Y, Ogundele A, Fulcher

N, Acs A, Moore-Schiltz L, Karpecki PM. Real-World Treatment Patterns Of Cyclosporine Ophthalmic Emulsion And Lifitegrast Ophthalmic Solution Among Patients With Dry Eye. Clin Ophthalmol. 2019 Nov 22;13:2285-2292.Topical ocular reproxalap is

an investigational new drug candidate that has been studied in more than 1,800 patients with no observed safety concerns; mild and transient instillation site discomfort is the most commonly reported adverse event in clinical trials. Over

the past ~12 months, Aldeyra has met with 40 MDs and 25 ODs, attended 8 conferences, and published 1 abstract and 6 peer-reviewed manuscripts. In conjunction with ClearView Healthcare Partners, Aldeyra has completed target product profile

testing with 40 eyecare professionals and 20 dry eye disease patients. With lifitegrast and cyclosporine, ~60%-70% of patients discontinue treatment with median time to discontinuation of ~1 month and ~3 months, respectively.* Among

healthcare providers, the target product profile of rapid onset of action and improvement in dryness symptoms was viewed as highly favorable. Among dry eye disease patients, the target product profile of reduction in symptoms and redness

was viewed as highly favorable. Pending FDA feedback, reproxalap, if approved, has the potential to be the first drug label to include clinical data for multiple objective signs of dry eye disease.

With Currently Available Dry Eye Disease Therapies, Discontinuation and Switching Rates are Early and

Prevalent for Most Patients Sources: White DE, Zhao Y, Ogundele A, Fulcher N, Acs A, Moore-Schiltz L, Karpecki PM. Real-World Treatment Patterns Of Cyclosporine Ophthalmic Emulsion And Lifitegrast Ophthalmic Solution Among Patients With Dry

Eye. Clin Ophthalmol. 2019 Nov 22;13:2285-2292. Eyecare provider Interviews; ClearView analysis of market research conducted Q4 2021 - Q1 2022. All trademarks are the property of their respective owners. Switching Median of 76 days 9.6%

switch from Xiidra to Restasis SwitchingMedian of 124 days 5.0% switch from Restasis to Xiidra Remaining At one year 27.5% remaining on Restasis Reinitiation Median of 174 days 9.0% reinitiation Discontinuation Median of 29

days 64.4% discontinued within first year Discontinuation Median of 89 days 70.8% discontinued within first year Reinitiation Median of 206 days 15.7% reinitiation Restasis Xiidra Remaining At one year 31.7% remaining on

Xiidra For Restasis and Xiidra, patients filled an average of four months' supply over the course of one year. Illustrative Patient Experience with Restasis and Xiidra in Year One Key: Patients on Restasis Patients on

Xiidra Patients on neither There is substantial opportunity for reproxalap, if approved, to capture patients that need a prescription therapy but have discontinued. Eyecare providers noted patient education regarding realistic

expectations for time to symptom relief and side effects helped discontinued patients reinitiate or switch to a new therapy. ~70% of patients who have tried Restasis or Xiidra are no longer on those therapies and may be seeking new

Dryness Source: Eyecare provider Interviews (n=40); ClearView analysis of market research conducted Q4

2021 - Q1 2022. Topical ocular reproxalap is an investigational new drug candidate that has been studied in more than 1,800 patients with no observed safety concerns; mild and transient instillation site discomfort is the most commonly

reported adverse event in clinical trials. Rapid onset of action is differentiated from existing options and likely to improve compliance. Ocular dryness and related symptoms are the key metrics for activity in dry eye disease. Redness

improvement may allow for reduction in number of therapies used (e.g., not needing vasoconstrictors). Key Healthcare Provider Feedback Key Drivers of Eyecare Provider Enthusiasm "Getting the patient comfortable by reducing dryness is

what's most important." - SO Ophtho. Considered an important measure of efficacy as dryness is a common driver of patient discomfort Surveyed Eyecare Providers Viewed Reproxalap's Potential Benefits Highly Favorably Redness "I have some

patients who complain about redness, and this could help with compliance for them." - HP Optom. 15 - 30% of DED patients report redness as a driving concern Enthusiasm Enthusiasm Strength of Value Proposition Onset of

Action "Significant dryness improvement in 8 days is impressive and highly valuable." - MO Ophtho. Rapid impact on dryness may improve patient compliance 90-minute redness reduction is valuable for a subset of

patients Enthusiasm Low High Low High Low High 14

Patient Research Indicates Value for a Dry Eye Disease Therapy that May Reduce Symptomatic Burden and

Ocular Redness Source: Patient Interviews (n=40); ClearView analysis of market research conducted Q4 2021 - Q1 2022. Topical ocular reproxalap is an investigational new drug candidate that has been studied in more than 1,800 patients with no

observed safety concerns; mild and transient instillation site discomfort is the most commonly reported adverse event in clinical trials 15 Efficacy Feedback (Patients) "The eye dryness is so terrible it really does affect my daily life.

I love that this drug is going after dryness." - Severe Patient "I don't think I would take a drug if it didn't help my dryness because that's my biggest problem." - Moderate Patient "My eyes get red sometimes. Its annoying so I guess the

fact that this targets redness too is a bonus." - Severe Patient "I hate when my eyes are red. This sounds amazing because it can help my dry eye and resolve my redness!" - Moderate Patient "My eyes never really get red, so I don't care

very much about the redness endpoint." - Moderate Patient "I definitely care about my dryness being resolved first before anything else." - Mild Patient Patients noted ocular dryness as one of their top complaints amongst symptoms of dry